Latent mercaptans as multi-functional additives for halogen-containing polymer compositions

ABSTRACT

Halogen-containing polymer compositions comprising a latent mercaptan-containing heat stabilizer composition substantially free from the offensive odor typically associated with mercaptans are protected during processing by the degradation products of the latent (i.e., blocked) mercaptan which include a free mercaptan. Other products of the degradation are believed to include carbocations of the blocking moiety which are stabilized by a molecular structure in which the electron deficiency is shared by several groups. The latent mercaptan may be the sole heat stabilizer additive but the free mercaptan released during processing may also synergize the activity of metal-based heat stabilizers such as metal salts and organometallic stabilizers such as organotin carboxylates and mercaptides in the polymer composition. The odor of primary mercaptan-containing heat stabilizers in halogenated polymer compositions is masked by a small amount of a latent mercaptan. The latent mercaptans also serve as intermediates in the preparation of anti-oxidants, anti-microbial agents, photostabilizers, and primary heat stabilizers. Highly effective heat stabilizers are prepared by the condensation of formaldehyde and a para-phenol and further condensation of the crude product with a mercapto-containing compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending application U.S. Ser. No.09/008,542, filed Jan. 16, 1998, which was a continuation-in-part ofapplication U.S. Ser. No. 08/597,093, filed Feb. 23, 1996, nowabandoned, which was a continuation-in-part of application U.S. Ser. No.08/435,413, filed May 10, 1995, now abandoned.

FIELD OF THE INVENTION

This invention relates to stabilizer compositions comprising degradationproducts of a blocked mercaptan present during processing of thecomposition at an elevated temperature, said products including a freemercaptan. This invention also relates to polymer compositionscontaining a polymer normally susceptible to heat-induced deteriorationand the degradation products of a blocked mercaptan present duringprocessing of the composition at an elevated temperature, said productsincluding a free mercaptan. It also relates to such polymer compositionsfurther containing a metallic-based heat stabilizer. This invention alsorelates to articles of manufacture, e.g. pipe, film, and window profile,made from stabilized polymer compositions containing a polymer normallysusceptible to heat-induced deterioration, the degradation products of ablocked mercaptan present during processing of the composition at anelevated temperature, said—based heat stabilizer. Another aspect of thisinvention is the development of a novel reaction scheme which, althoughcrude, affords latent mercaptans which need no purification to be highlyactive PVC heat stabilizers at low use levels.

This invention also relates to latent mercaptans which are substantiallyfree of the offensive odor typical of mercaptans and which may be usedas anti-oxidants, odorants, anti-microbial agents chelating agents andphotostabilizers; and as intermediates for the preparation ofanti-oxidants and primary heat stabilizers. It also relates to suchanti-oxidants and primary heat stabilizers.

BACKGROUND OF THE INVENTION

It is well known that the physical properties of various organicpolymers deteriorate and color changes take place during processing ofthe polymer and during exposure of formed polymer products to certainenvironments. The prime examples of polymers which are susceptible todegradation during processing are the halogen-containing polymers suchas the vinyl and vinylidene polymers in which the halogen is attacheddirectly to carbon atoms. Poly (vinyl chloride) or PVC, copolymers ofvinyl chloride and vinyl acetate, and poly (vinylidene chloride), theprincipal resin in self-clinging transparent food wraps, are the mostfamiliar polymers which require stabilization for their survival duringfabrication into pipes, window casings, siding, bottles, and packagingfilm, etc. When such polymers are processed at elevated temperatures,undesirable color changes often occur within the first 5 to 10 minutesas well as during later stages of the processing. Haziness, whichsometimes accompanies the color changes, is particularly undesirablewhere clear products are needed. The addition of heat stabilizers tosuch polymers has been absolutely essential to the wide-spread utilityof the polymers. From a great deal of work in the development of moreand more effective heat stabilizers there has emerged two principalclasses: organotin compounds and mixed metal combinations.Organotin-based heat stabilizers are the most efficient and widely usedPVC stabilizers. Synergistic combinations of alkyltin mercaptides andfree mercaptans are particularly efficient heat stabilizers for PVCduring extrusion. They have not been entirely satilsfactory, however,because of several failings on the part of the mercaptan synergist. Manymercaptans give off an offensive odor even at room temperature and theodor grows worse at PVC processing temperatures. The oxidative stabilityof the mercaptans is very often very poor. Oxidation of the freemercaptans diminishes the synergism. Thus, a combination having anenhanced synergism would be welcomed by the PVC industry. Also, becauseof the end-use of articles made from some polymers, many polymericcompositions require the presence of both biocides and heat stabilizersbut the use of the organotin mercaptide/mercaptan combination in such acomposition is often frustrated by the tendency of the free mercaptan todeactivate a biocide such as the much used OBPA (10,10′-oxybisphenoxarsine).

In U.S. Pat. No. 3,660,331, Ludwig teaches the stabilization of vinylhalide resins by certain thioethers and thioesters of tetrahydropyran.Better heat stabilizer compositions are still needed, however. Thethioethers of this invention satisfy that need.

SUMMARY OF THE INVENTION

It is an object of this invention, therefore, to provide a heatstabilizer composition having the synergy of a mercaptan plus improvedoxidative stability.

It is another object of this invention to provide a latentmercaptan-containing heat stabilizer composition which is substantiallyfree from the offensive odor typically associated with mercaptans.

It is a related object of this invention to provide a latentmercaptan-containing heat stabilizer composition which has a decidedlypleasant odor.

It is a further object of this invention to provide in improvedpolymeric composition containing a biocide and a latentmercaptan-containing heat stabilizer.

It is a related object of this invention to provide a polymericcomposition containing a heat stabilizer combination having the synergyof a mercaptan plus improved oxidative stability.

It is still another object of this invention to provide latentmercaptans as intermediates for the preparation of anti-oxidants,anti-microbial agents, photostabilizers, and primary heat stabilizers.

These and other objects of the invention which will become apparent fromthe following description are achieved by incorporating into a polymericcomposition containing a polymer normally susceptible to heat-induceddeterioration a blocked mercaptan which degrades during processing ofthe composition at an elevated temperature to liberate a free mercaptan.The latent mercaptan may act as the sole heat stabilizer but the freemercaptan may also synergize the activity of other heat stabilizers inthe composition. Other products of the degradation of the blockedmercaptan are believed to include carbocations of the blocking moietywhich are stabilized by a molecular structure in which the electrondeficiency is shared by several groups. Resonance stabilization andneighboring group stabilization are two of the possible mechanisms bywhich the carbocations may be stabilized. The carbocations act asintermediates in the formation of stable compounds early in the hotprocessing of halogen-containing polymers. Although such mechanisms andthe resultant carbocations are believed to be an impetus for theliberation of the active free mercaptan, this invention is in no waylimited by the foregoing attempt to explain the working of theinvention. Those skilled in the art will see the resonance stabilizationand neighboring group stabilization that are possible in the followingstructures of the blocked mercaptan; other mechanisms may be at work inother blocked mercaptans represented by these structures that alsoliberate an active free mercaptan upon thermal and/or chemicaldegradation during processing of polymeric compositions containing suchblocked mercaptans. For the purposes of this invention, the terms“blocked mercaptan” and “latent mercaptan” are used interchangeably tomean a thioether which degrades during processing of the composition atan elevated temperature to liberate a free mercaptan.

The stabilizer compositions of the present invention may comprise ametal-based stabilizer and such a latent mercaptan or mixture of latentmercaptans.

DETAILED DESCRIPTION OF THE INVENTION

As used herein: the terms “group” and “radical” are usedinterchangeably, a mono-valent radical has but one valence available forcombining with another radical whereas a di-valent radical may combinewith two other radicals; the term alkyl represents monovalent straightor branched chain hydrocarbon radicals containing, for example, 1 to 20carbon atoms; the term alkylenyl represents divalent, trivalent, andtetravalent straight or branched chain hydrocarbon radicals containing,for example, 1 to 20 carbon atoms; the term aryl represents monovalentC₆-C₁₀ aromatic rings such as benzene and naphthalene; the term alkenylrepresents monovalent straight or branched chain C₂ to C₂₀ hydrocarbonradicals containing at least one double bond; the term aralkylrepresents a monovalent C₁ to C₂₀ hydrocarbon radical having attachedthereto an aryl radical; the term alkaryl represents monovalent arylradicals having attached thereto at least one C₁-C₂₀ alkyl group; theterm cycloalkyl represents monovalent C₃-C₂₀ saturated cycloaliphaticradicals; the term cycloalkenyl represents C₅-C₈ cycloaliphatic radicalscontaining at least one double bond; the term polyalkoxy means a chainof from 2 to 6 alkoxy groups wherein the alkoxy group is ethoxy,propoxy, isopropoxy, butoxy, or the like, with or without an end groupsuch as hydroxy, acyloxy, benzyloxy, benzoyloxy, butoxy, andtetrahydropyranyloxy; the term halogen-containing organic polymersrepresents halogen-containing vinyl and vinylidene polymers or resins inwhich the halogen is attached directly to the carbon atoms.

Also, as used herein: an acyloxyalkyl radical originatos from acarboxylic acid ester of an alkyl alcohol; the R¹ radical in Formula 1below, therefore, in the stearic acid ester of mercaptopropanol is thestearoyloxypropyl radical; likewise, the R¹ radical of the oleic acidester of mercaptopropanol, which is one the tallate esters of thatalcohol, is the oleoyloxypropyl radical; the R¹ radical oflauryl-3-mercaptopropionate, on the other hand, isdodecyloxy-carbonylpropyl.

The polymeric compositions of this invention contain polymers normallysusceptible to heat-induced deterioration through autoxidation such asthe above-noted halogen-containing polymers. The stabilizer compositionsof this invention are particularly suited to impart a superiorstabilization against the deteriorative effects of heat and ultra-violetlight on halogen-containing organic polymers compared to that impartedby stabilizer compositions previously known in the art.

The halogen-containing organic polymers which can be stabilizedaccording to this invention include chlorinated polyethylene having 14to 75%, e.g. 27%, chlorine by weight, chlorinated natural and syntheticrubber, rubber hydrochloride, chlorinated polystyrene, chlorinatedpolyvinyl chloride, polyvinyl bromide, polyvinyl fluoride, copolymers ofvinyl chloride with 1 to 90%, preferably 1 to 30%, of a copolymerizableethylenically unsaturated material such as, for example, vinyl acetate,vinyl butyrate, vinyl benzoate, vinylidene chloride, diethyl fumarate,diethyl maleate, other alkyl fumarates and maleates, vinyl propionate,methyl acrylate, 2-ethylhexyl acrylate, butyl acrylate and other alkylacrylates, methyl methacrylate, ethyl methacrylate, butyl methacrylateand other alkyl methacrylates, methyl alpha-chloroacrylate, styrene,trichloroethylene, vinyl ethers such as vinyl ethyl ether, vinylchloroethyl ether and vinyl phenyl ether, vinyl ketones such as vinylmethyl ketone and vinyl phenyl ketone, 1-fluoro-2-chloroethylene,acrylonitrile, chloroacrylonitrile, allylidene diacetate andchloroallylidene diacetate. Typical copolymers include vinylchloride-vinyl acetate (96:4 sold commercially as VYNW), vinylchloride-vinyl acetate (87:13), vinyl chloride-vinyl acetate-maleicanhydride ((86:13:1), vinyl chloride-vinylidene chloride (95:5); vinylchloride-diethyl fumarate (95:5), and vinyl chloride 2-ethylhexylacrylate (80:20). In addition to the stabilizer compositions of thisinvention, there can also be incorporated into the halogen-containingorganic polymer conventional additives such as plasticizers, pigments,fillers, dyes, ultraviolet light absorbing agents, densifying agents,biocides and the like.

Preferably, the halogen-containing organic polymer is a vinyl halidepolymer, more particularly a vinyl chloride polymer. Usually, the vinylchloride polymer is made from monomers consisting of vinyl chloridealone or a mixture of monomers comprising, preferably, at least about70% by weight based on the total monomer weight of vinyl chloride.

FORMULA 1 is representative of the blocked mercaptans that are suitablefor the purposes of this invention:

wherein a is 0 or 1, m and n are 0 or 1; y=1 to 4; when y=1, z is 1 to4; and when y is more than 1, z is 1; R1 is an alkyl, alkylenyl,cycloalkyl, cycloalkylenyl, aryl, alkaryl, aralkyl, aralkylenyl,hydroxyalkyl, dihydroxyalkyl, hydroxy(polyalkoxy)alkyl, alkoxyalkyl,hydroxyalkoxyalkyl, alkoxy(hydroxyalkyl), alkoxy(acyloxyalkyl),alkoxy(polyalkoxy)alkyl, alkoxy(polyalkoxy)carbonylalkyl, carboxyalkyl,acyloxyalkyl, acyloxy(hydroxyalkyl), acyloxyalkoxyalkyyl,acyloxy(polyalkoxy)alkyl, benzoyloxy(polyalkoxy)alkyl,alkylenebis-(acyloxyalkyl), alkoxycarbonylalkyl,alkoxycarbonylalkylenyl, hydroxyalkoxycarbonylalkyl,hydroxy(polyalkoxy)carbonylalkyl, mercaptoalkyl, mercaptoalkylenyl,mercaptoalkoxycarbonylalkyl, mercaptoalkoxycarbonylalkylenyl,alkoxycarbonyl(amido)alkyl, alkylcarbonyloxy(polyalkoxy)carbonylalkyl,tetrahydopyranyloxy(polyalkoxy)carbonylalkyl, tetrahydropyranyloxyalkyl,hydroxyaryl, mercaptoaryl or carboxyaryl radical having from 1 to 22carbon atoms; R², R³, R⁴, R⁵, R⁶, and R⁷ are independently hydrogen, ahydroxyl, mercapto, acyl, alkyl, alkylenyl, aryl, haloaryl, alkaryl,aralkyl, hydroxyalkyl, mercaptoalkyl, hydroxyaryl, alkoxyaryl,alkoxyhydroxyaryl, mercaptoaryl groups having from 1 to 22 carbon atoms;X is aryl, haloaryl, alkaryl, hydroxyaryl, dihydroxyaryl, alkoxyaryl,arylcycloalkyl, or a heteroatom, with the option that when a is 1 and mis 1, R⁶ and R⁷ form a heterocyclic moiety in conjunction with X asnitrogen, and with the further option that when a=1 and m 0, one of R¹,R³, and R⁵ joins with R⁷ and X to form a heterocyclic moiety with X as aheteroatom selected from the group consisting of oxygen and sulfur; withthe proviso that z is 1 or 2 when X is aralkaryl, R⁶ and R⁷ arehydroxyl, a is 1 and m is 1, and with the further proviso that whenR⁶≠hydroxyl or mercapto, z is 1.

A polymeric composition wherein the blocked mercaptan has the followingstructure is another embodiment of this invention:

wherein a is 0 or 1, m and n are 0 or 1; y=1 to 4, when y=1, z is 1 to 4when y is more than 1 z is 1; R1 is an an alkyl, alkylenyl, cycloalkyl,cycloalkylenyl, aryl, alkaryl, aralkyl, aralkylenyl, hydroxyalkyl,dihydroxyalkyl, hydroxy(polyalkoxy)alkyl,alkoxy(polyalkoxy)carbonylalkyl, alkoxyalkyl, hydroxyalkoxyalkyl,alkoxy(hydroxyalkyl), alkoxy(acyloxyalkyl), alkoxy(polyalkoxy) alkyl,carboxyalkyl, acyloxyalkyl, acyloxy(hydroxyalkyl), acyloxyalkoxyalkyl,acyloxy(polyalkoxy)alkyl, benzoyloxy(polyalkoxy)alkyl,alkylenebis-(acyloxyalkyl), alkoxycarbonylalkyl,alkoxycarbonylalkylenyl, hydroxyalkoxycarbonylalkyl,hydroxy(polyalkoxy)carbonylalkyl, mercaptoalkyl, mercaptoalkylenyl,mercaptoalkoxycarbonylalkyl, mercaptoalkoxycarbonylalkylenyl,alkoxycarbonyl(amido) alkyl, alkylcarbonyloxy(polyalkoxy)carbonylalky,tetrahydopyranyloxy(polyalkoxy)carbonylalkyl, tetrahydropyranyloxyalkyl,hydroxyaryl, mercaptoaryl or carboxyaryl radical having from 1 to 22carbon atoms; R², R³, R⁴, R⁵, R⁶, and R⁷ are independently hydrogen, ahydroxyl, mercapto, alkyl, alkylenyl, aryl, haloaryl, alkaryl, aralkyl,hydroxyalkyl, mercaptoalkyl, hydroxyalkylmercaptoalkyl,mercaptoalkylenyl, hydroxyaryl, alkoxyaryl, alkoxyhydroxyaryl,arylcarbonyl, or mercaptoaryl radical having from 1 to 22 carbon atoms;when a=1, X is arylcycloalkyl or a heteroatom, and when a=0, X is aryl,haloaryl, alkaryl, alkoxyaryl, arylcycloalkyl, or a heteroatom, with theoption that when a is 1 and m is 0, one of R3 and R⁵ joins with R⁷ and Xto form a heterocyclic moiety with X as a heteroatom selected from thegroup consisting of oxygen and sulfur, and with the further option thatwhen a is 1 and m is 1, R⁶ and R⁷ form a heterocyclic moiety inconjunction with X as a nitrogen atom.

The mercaptan-containing organic compounds which may be converted intolatent mercaptans for the purposes of this invention are well-knowncompounds and include alkyl mercaptans, mercapto esters, mercaptoalcohols, and mercapto acids. See, for example, U.S. Pat. Nos. 3,503,924and 3,507,827. Alkyl mercaptans having from 1 to about 200 carbon atomsand from 1 to 4 mercapto groups are suitable. Mercaptan-containingorganic compounds which include R¹ have structures illustrated by thefollowing formulas:

wherein

R¹⁰ and R¹⁹ are the same or different and are

 —OH, —SH, aryl, C₁ to C₁₈ alkyl, or —H;

R¹¹ is —H, aryl, or C₁ to C₁₈ alkyl;

R¹² is cycloalkyl, cycloalkenyl or phenyl;

R¹³ is

 —SH, aryl, C₁ to C₁₈ alkyl, —OH or —H with the proviso that in formula(MC2) when R¹² is phenyl, R¹³ is —OH and i=0, then the —SH groups are onnon-adjacent carbon atoms;

R¹⁴ is —H or a divalent group which may contain halogen, hydroxy,mercapto or alkyl substituents and which when R¹² is phenyl combineswith the phenyl to form a naphthalene ring;

R¹⁵ is

R¹⁷ is —H, or alkyl, alkenyl, aryl, aralkyl, alkaryl, cycloalkyl,cycloalkylenyl;

R¹⁸ is arylene, C₁ to C₈ alkylenyl,

wherein b is an integer from 1 to 6;

i=0 or an integer from 1 to 6 inclusive;

j=0, 1, 2 or 3; and

f=1 or 2.

Mercaptan-containing organic compounds preferred as intermediates in thepreparation of the latent mercaptans of this invention are thosecompounds according to formula (MC1) where R¹¹ is —H, R¹⁹ is —H, R¹⁰ isOH or

and i=1; those compounds according to formula (MC2) where R¹² is phenyl,R¹¹ is —H, R¹³ is —H, R¹⁴ is —H, i=1, and j=1; those compounds accordingto formula (MC3) where R¹¹ is —H, R¹⁵ is

and i=1; those compounds according to formula (MC4) where R¹¹ is —H andi=1; those compounds according to formula (MC5) where R¹⁶ is —C₂H₅ or

R¹¹ is —H and i=1; and those compounds according to formula (MC6) whereR¹¹ is —H and i=1.

Examples of the mercaptan-containing organic compounds described byformula (MC1) include, but are not limited to, the following compounds:

Examples of the mercaptan-containing organic compounds described byformula (MC2) include, but are not limited to, the following compounds:

Examples of mercaptan-containing organic compounds represented byformula (MC3) include, but are not limited to the following compounds:

The mercaptan-containing organic compounds described by formula (MC4)are exemplified by, but are not limited to, the following:

The mercaptan-containing organic compounds represented by formula (MC5)are exemplified by, but are not limited to, the following:

The mercaptan-containing organic compounds represented by formula (MC6)are exemplified by, but are not limited to, the following:

One of the advantages of this invention is that the offensive odor ofthe mercaptans is masked by the blocking group so that the latentmercaptan thus created may be put into a PVC composition or the likewith little or no offense to the operator with the knowl-edge that thefree mercaptan will be released as a degradation product when thetreated composition is heated during the usual processing, e.g.extrusion. This advantage is also useful for the liquid polysulfideshaving a molecular weight of from about 1000 to about 8000 sold underthe LP trademark by Morton International, Inc.

The blocking compounds are preferably those which are capable offurnishing a stabilized carbocation having a molecular structure inwhich the electron deficiency is shared by several groups. Resonancestabilization and neighboring group stabilization are two of thepossible mechanisms by which the carbocations may be stabilized.Polarized, unsaturated compounds exemplified by 3,4-dihydropyran,2-methoxy-3,4-dihydropyran, styrene, α-methylstyrene, vinyl benzylchloride, indene, 2-vinylpyridine, N-vinylpyrrolidone, vinyl acetate,octadecyl vinyl ether, cyclohexyl divinyl ether, ethyleneglycolmonovinyl ether, allyl phenyl ether, trans-cinnamaldehyde,N-methyl-N-vinylacetamide, N-vinylcaprolactam, isoeugenol, and2-propenylphenol are suitable. Compounds having labile halogen atomswhich split off as hydrogen chloride in a condensation reaction with themercaptan, as exemplified by triphenylmethyl chloride, benzyl chloride,and bis(chloromethyl) benzene, are also suitable. The mercaptan may alsobe blocked by condensation with an aldehyde such as butyraldehyde orwith a benzyl alcohol such as benzene dimethanol. A preferred blockingagent is 2-hydroxybenzyl alcohol, a well known intermediate in theperfume, agricultural, and plastics industries.

In general, the procedure for adding the mercapto group of a freemercaptan across the double bonds of polarized, unsaturated compoundsis:

To a stirred mixture of the mercaptan, acid catalyst, and optionally, asmall percentage of antioxidant to irhibit radical reactions, undernitrogen atmosphere is added dropwise the polarized, unsaturatedcompound, either neat or in solution, while maintaining the temperaturebetween 10°-70° C. The mixture or solution is then heated for between 1to 6 hours at 35°-70° C. and conversion to product is monitored by gaschromatography and iodine titration for SH. The acid catalyst is removedby an alkaline wash and the resulting product is dried with magnesiumsulfate and filtered. The solvent, if required, is removed under reducedpressure at <50° C. to yield the latent mercaptan. This generalizedprocedure is referred to hereinafter as Procedure A.

In accordance with Procedure A, for example, mercaptoethanol is addedacross the double bond of N-vinylcaprolactam to yieldN-2-hydroxyethylthioethylcaprolactam. Mercaptoethyldecanoate (ormercaptoethylcaproate) reacts with 3,4-dihydropyran in that procedure togive 2-S-(tetrahydropyranyl)thioethyldecanoate.Bis(hydroxyethylthioethyl) cyclohexyl ether is made from themercaptoethanol and cyclohexyl di-vinyl ether. In like manner, thecorresponding caprate, oleate, and tallate esters form the correspondingcyclohexyl ethers. Also, indene is converted by the addition of themercaptoethanol to 2H-dihydroindenylthio-ethanol.

A generalized procedure for the condensation of a free mercaptan with alabile halogen-containing compound is as follows:

To a stirred mixture of the mercaptan and halogen-containing compoundunder nitrogen atmosphere is added dropwise a solution of sodiummethoxide in methanol while maintaining the temperature below 50° C.Optionally, the reaction is allowed to proceed without the addition of abase source and the liberated hydrogen chloride is removed by nitrogengas sweep and neutralized with the use of an external acid scrubber. Themixture or solution is then heated for between 2 to 24 hours at 50°-70°C. and conversion to product is monitored by gas chromatography andiodine titration for %SH. The product is then neutralized, washed withwater, dried with magnesium sulfate, and filtered. The solvent, ifrequired, is removed under reduced pressure at <50° C. to yield thelatent mercaptan. This generalized procedure is referred to hereinafteras Procedure B.

A generalized procedure for the condensation of a free mercaptan with alabile hydroxyl-containing compound is as follows:

To a stirred solution of the mercaptan, acid catalyst, and solvent undernitrogen atmosphere is added the hydroxy-containing compound either neator in solution while maintaining the temperature <45° C. The solution isthen heated to 45°-75° C. for between 1 to 10 hours and conversion toproduct is monitored by gas chromatography and iodine titration for %SH.Optionally, an azeotropic solvent is chosen for removal of reactionwater by an appropriate means at reflux temperatures, typically 60°-120°C. Completion of reaction is achieved after the theory amount of waterhas been collected. The acid catalyst is removed by alkaline wash andthe resulting solution is dried with magnesium sulfate and filtered. Thesolvent is removed under reduced pressure at <55° C. to yield the latentmercaptan. This procedure is referred to hereinafter as Procedure C.

For example, 2-hydroxybenzyl alcohol condenses with mercaptoethanol inaccordance with Procedure C to form1-(2-hydroxyphenyl)-1-S-(2-hydroxyethylthio)methane.

A generalized procedure for the reaction of a free mercaptan with aglycidyl ether is as follows:

To a stirred mixture of the mercaptan and acid catalyst under nitrogenatmosphere is added the glycidyl ether, either neat or in solution,while maintaining the temperature between 25°-60° C. The mixture orsolution is then heated to between 50°-75° C. for a period of 1 to 6hours and conversion to product is monitored by gas chromatography andiodine titration for %SH. The acid catalyst is removed by alkaline wash,the resulting product is dried with magnesium sulfate, and filtered. Thesolvent, if required, is removed under reduced pressure at <55° C. toyield the latent mercaptan. For example, the reaction betweenmercaptoethanol and glycidyl neodecanoate givesC₉H₁₉C(═O)OCH₂CH(OH)CH₂SCH₂CH₂OH. This procedure is referred tohereinafter as Procedure D.

A generalized procedure for the condensation of a free mercaptan with analdehyde is as follows:

To a stirred solution of the mercaptan, acid catalyst, and azeotropicsolvent under nitrogen atmosphere is added the aldehyde with heating toreflux, typically between 65°-120° C., for removal of reaction water.Completion of reaction is achieved after the theory amount of water hasbeen collected. Optionally, to a stirred solution of mercaptan,aldehyde, and ether is added BF₃-etherate dropwise under refluxconditions. The solution is refluxed for between 1 to 6 hours andconversion to product is monitored by gas chromatography. The acidcatalyst is removed by alkaline wash, the solution is dried withmagnesium sulfate and filtered. The solvent is removed under reducedpressure at <65° C. to yield the latent mercaptan. This generalizedprocedure is referred to hereinafter as Procedure E.

Examples of the blocked mercaptans of this invention include compoundshaving the following formulas, as each relates to FORMULA 1:

FORMULA

a=1, m=1, n=0; y=1, z is 1; X is nitrogen, R⁶ and R⁷ are joined to form—CH₂—CH₂—CH₂—C═(O)—; R⁴ is hydrogen; R⁵ is methyl; and R¹ ishydroxyethyl.

a=1, m=1, n=0; y=1, z is 1; X is nitrogen, R⁶ is acetyl, R⁷ is methyl,R⁵ is methyl, R⁴ is hydrogen, and R¹ is hydroxyethyl.

a=1, m 0, n=0; y=1, z is 1; X is oxygen, R⁵ and R⁷ are joined to form—CH₂—C₂—C₂—C₂—; R⁴ is hydrogen, and R¹ is hydroxyethyl.

a=1, m=0, n=1, y=1, z=1; X is oxygen, R³ and R⁷ join to form—CH₂—C₂—C₂—; R², R⁴ and R⁵ are hydrogen, and R¹ is hydroxyethyl.

a=1, m=0, n=0, y=1, z=1; X is oxygen, R⁵ and R⁷ join to form—CH₂—C₂—C₂—C₂—; R⁴ is hydrogen, and R¹ is 2-ethoxytetrahydropyranyl.

a=1, m=0, n=0, y=1, z=1; X is oxygen, R⁵ and R⁷ join to form—CH₂—C₂—C₂—C₂—; R⁴ is hydrogen, and R¹ is 3-ethoxytetrahydropyranyl.

a=1, m=0, n=1, y=1, z=1; X is oxygen, R³ and R⁷ join to form—CH₂—C₂—C₂—; R², R⁴ and R⁵ are hydrogen, and R¹ is2-ethoxytetrahydropyranyl.

a=1, m=0, n=1, y=1, z=1; X is oxygen, R³ and R⁷ join to form—CH₂—C₂—C₂—; R², R⁴ and R⁵ are hydrogen, and R¹ is3-ethoxytetrahydropyranyl.

a=0, m=0, n=0, y=1, z=1; X is phenyl, R⁴ is methyl, R⁵ is hydrogen, andR¹ is hydroxyethyl.

a=0, m=0, n=1, y=1, z=1, X is phenyl, R², R³, R⁴, and R⁵ are hydrogen,and R¹ is hydroxyethyl.

a=0, m=0, n=0, z=1; y=1, X is phenyl, R⁴ and R⁵ are hydrogen, and R¹ ishydroxyethyl.

a=1, m=0, n=0, y=1, z=1; X is phenyl, R⁴ and R⁵ are hydrogen, R⁷ iso-hydroxy, and R¹ is hydroxyethyl.

a=0, m=0, n=0, y=1, z=1; X is phenyl, R⁴ and R⁵ are hydrogen, and R¹ ismercaptoethoxycarbonylmethyl.

a=1, m=0, n=1, y=1, z=1; X is oxygen, R², R⁴ and R⁵ are hydrogen, R³ ismethyl, R⁷ is phenyl, and R¹ is hydroxyethyl.

a=1, m=0, n=0, y=1, z=1; X is oxygen, R⁷ and R¹ are joined to form anethylenyl radical, R⁴ is hydrogen, and R⁵ is propyl.

a=0, m=1, n=1, y=1, z=1; X is oxygen, R², R³, R⁶ and R⁴ are hydrogen, R⁵is 2-methyleneoxytolyi, and R¹ is hydroxyethyl.

a=1, m=0, n=1, y=1, z=1; X is oxygen, R², R³, R⁴ and R⁷ are hydrogen, R⁵is butoxymethyl, and R¹ is hydroxyethyl.

a=1, m=0, n=0, y=1, z=1; X is phenyl, R⁴ is hydrogen, R⁵ is ethyl, R⁷ iso-hydroxy, and R¹ is hydroxyethyl.

a=1, m=0, n=1, y=1, z=1; X is phenyl, R³, R⁴ and R⁵ are hydrogen, R² ismethyl, R⁷ is o-hydroxy, and R¹ is hydroxyethyl.

a=1, m=0, n=0, y=1, z 2; X is phenyl, R⁴ is hydrogen, R⁵ is ethyl, R⁷ iso-hydroxy, and R¹ is hydroxyethyl.

a=1, m=0, n=0, y=1, z=1; X is m-methoxyphenyl, R⁴ is hydrogen, R⁵ isethyl, R⁷ is p-hydroxy, and R¹ is hydroxyethyl.

a=0, m=0, n=0, y=1, z=2; X is tetrachlorophenyl, R⁴ and R⁵ are hydrogen,and R¹ is hydroxyethyl.

a=1, m=0, n=0, y=1, z=1; X is o,p-dihydroxyphenyl, R⁷ ism-phenylcarbonyl, R⁴ is hydrogen, R⁵ is —CH₂CH₃, and R¹ is hydroxyethyl.

a=1, m=0, n=0; y=1, z is 1; X is oxygen, R⁵ and R⁷ are joined to form—CH₂—C₂—C₂—C₂—; R⁴ is hydrogen, and R¹ is decanoyloxyethyl.

a=1, m=0, n=0; y=1, z is 1; X is p-hydroxyphenyl, R⁴ and R⁵ arehydrogen, R⁷ is m-methoxy, and R¹ is hydroxyethyl.

As stated above, the stabilizer compositions of the present inventioncomprise a latent mercaptan as the sole heat stabilizer or in a systemcomprising a metal-based stabilizer, an organic-based stabilizer, or ahydrotalcite-based stabilizer in admixture with the latent mercaptan.Metal-based stabilizers are defined for the purposes of this inventionas metal salt stabilizers and organometallic stabilizers. The metal saltstabilizers are exemplified by barium, strontium, calcium, cadmium,zinc, lead, tin, magnesium, cobalt, nickel, titanium, antimony, andaluminum salts of phenols, aromatic carboxylic acids, fatty acids,epoxidized fatty acids, oxalic acid, carbonic acid, sulfuric acid, andphosphoric acid. Calcium stearate, calcium 2-ethyl-hexeate, calciumoctoate, calcium oleate, calcium ricin-oleate, calcium myristate,calcium palmitate, calcium laurate, barium laurate, barium stearate,barium di(nonylphenolate), magnesium stearate, zinc stearate, zincoctoate, cadmium laurate, cadmium octoate, cadmium stearate, sodiumstearate and other Group I and II metal soaps are examples of suitablesalts. Other metal salts such as lead stearate, hydrotalcite, aluminumstearate, etc, can be used. Metal salt stabilizers may constitute fromabout 0.1 to about 10%, preferably 0.1-5% by weight of the halogencontaining resin.

Conventional organometallic stabilizers include the organotincarboxylates and mercaptides. Such materials include butyltin trisdodecyl mercaptide, dibutyltin dilaurate, dibutyltin didodecylmercaptide, dianhydride tris dibutylstannane diol, dihydrocarbontinsalts of carboxy mercaptals such as those set forth in Hechenbleikner etal.(U.S. Pat. No. 3,078,290). There can be included any of the vinylchloride resin stabilizers set forth in Salyer (U.S. Pat. No.2,985,617).

As an example of a system involving an organic-based stabilizer, acombination of a latent mercaptan and an N-substituted maleimide hasbeen found to be synergistic in the stabilization of a flexible PVCformulation.

The stabilizer compositions of this invention comprise from about 10% toabout 100%, preferably from about 35% to about 85%, by weight of one ormore latent mercaptans, based on the total weight of the stabilizercomposition, the balance comprising the metal-based, organic-based, orhydrotalcite-based stabilizer. Preferable, the stabilizer compositionsof this invention comprise a mono-organotin compound or mixture ofmono-organotin compounds, and, optionally, a diorganotin compound ormixture of diorganotin compounds or mixtures of mono-organotin anddi-organotin compounds. Thus, when no diorganotin compound or mixture ofdiorganotin compounds is employed in the preferred stabilizer of thisinvention, the mono-organotin compounds will comprise from about 10% toabout 90% by weight, preferably about 15% to about 65% by weight of thetotal weight of the stabilizer composition. When it is desirable toutilize a diorganotin compound or mixture of diorganotin compounds inthe practice of this invention, said diorganotin compound or mixture ofdiorganotin compounds may comprise from about 0.05% to about 75%, byweight, preferably from about 0.05% to about 35% by weight of the totalweight of the stabilizer composition.

The mono-organotin compounds useful in the compositions of thisinvention contain one or more tetravalent tin atoms each of which haveone direct tin to carbon bond and have structures selected from thefollowing formulas:

wherein Z and Z′ are the same or different and are selected from

with the proviso that in formula (E) when z=1 and in formulas (C) and(D) at least one Z or Z″ is —SR³²;

Y is

W and W¹ are the same or different and are oxygen or sulfur; R³⁰ and R³¹are the same or different and are selected from alkyi, aryl, alkenyl,aralkyl, alkaryl, cycloalkyl, cycloalkenyl,

R³² is alkyl, alkenyl, aryl, aralkyl, cycloalkyl, cycloalkenyl,

R³³ is alkyl, alkenyl, aryl, aralkyl, alkaryl, cycloalkyl, orcycloalkenyl;

R³⁴ is alkylene of at least 2 carbon atoms, arylene, alkenylene of atleast 2 carbon atoms, cycloalkylene, or cycloalkenylene;

R³⁵ is alkylene, arylene, alkenylene of at least 2 carbon atoms,cycloalkylene, or cycloalkenylene;

R³⁶ is R³⁴;

R³⁷ is nothing or R³⁵;

R³⁸ is C₁ to C₄ alkylenyl;

R³⁹ is —H or a monovalent C₁ to C₂₀ hydrocarbon radical;

R⁴⁰ and R⁴¹ are the same or different and are each C₁ to C₂₂ alkyl or C₁to C₂₀ alkoxy;

R⁴² is —H or R³³;

q=0 or an integer from 1 to 4 inclusive;

v=an integer from 1 to 8 inclusive; and

w=0, 1 or 2, x=0 or 1, z=0 or 1 with the proviso that when

x=0 then z=1, when x=1 then z=0 and w=1, when w=2 then x=0 and z=1, andwhen w=0 then x=0, z=1 and Y is —W—R³⁴—W¹— or

The preferred mono-organotin compounds useful in this invention arethose compounds according to formula (A) where R³⁰ is methyl, butyl oroctyl and W is sulfur; those compounds according to formula (B) whereR³¹ is methyl or butyl, W is sulfur, Z is —SR³² where R³² is

those compounds according to formula (C) where R³⁰ is methyl or butyl, Zis —SR³² where R³² is

those compounds according to formula (D) where R³⁰ is methyl, Z is —SR³²where R³² is

R³¹ is methyl, Z′ is —SR³² where R³² is

Y is —S—, and q=0; and those compounds according to formula (E) whereR³⁰ is methyl, Z is —SR³² where R³² is

R³¹ is methyl, Z′ is —SR³² where R³² is

Y is —S—, W=1, x=0, and z=1.

Examples of mono-organotin compounds which are useful in this inventioninclude, but are not limited to, those illustrated in Tables 1-4 below.Thus, representative of the mono-organotin compounds described byformulas (A) and (B) are those illustrated in Table 1 below.

TABLE 1 (A)

(B)

Mono-organotin Compound No. R³⁰ R³¹ W Z 1 —C₄H₉ — S — 2 —C₈H₁₇ — O — 3 ——CH₃ S

4 — —CH₃ S

5 —

S

Examples of mono-organotin compounds represented by formula (C) areillustrated in Table 2 below.

TABLE 2 R³⁰—Sn—Z₃ (C) Mono-organotin Compound No. R³⁰ Z 6 —CH₃

7 —C₄H₉

The mono-organotin compounds illustrated in Table 3 below arerepresentative of compounds described in formula (D).

TABLE 3 (D)

Mono-organotin Compound No. R³⁰ and R³¹ Z Z¹ Y q 8 —CH₃

Same as Z —S— 0 9

Same as Z —S—S— 0 10 —CH₃

Same as Z

1 11 —CH₃

Same as Z —S— 0 12 —C₄H₉

Same as Z

0 13 —CH₃

Same as Z —S— 0 14 —C₄H₉

Same as Z

0

The mono-organotin compound illustrated in Table 4 below isrepresentative of compounds described by formula (E).

TABLE 4 (E)

Mono-organotin Compound No. R³⁰ and R³¹ Z and Z¹ Y w x z 15 —CH₃

—S— 1 0 1

As used in Tables 1-3 above, and throughout this specification, theradicals —C₄H₉, —C₈H₁₇, —C₁₂H₂₅, —C₉H₁₉ and —C₁₀H₂₁ represent n-butyl,n-octyl, n-dodecyl, n-nonyl and n-decyl respectively.

The carboxyl radicals

are derived from oleic acid, scearic acid, n-octanoic acid, lauric acid,and pelargonic acid respectively. Likewise, the radicals —OC₁₃H₂₇,—OC₁₈H₃₇, and —OC₈H₁₇, are derived from tridecanol, stearyl alcohol andiso-octanol, respectively.

The diorganotin compounds useful in the practice of this inventioncontain one or more tetravalent tin atoms, at least one of which hasdirect bonds to two carbon atoms and have structure selected from thefollowing formulas:

wherein R³⁰ R³¹, W, Z, Z¹, Y, w and z are as previously defined; n=0, 1or 2, p=0, 1 or 2 with proviso that n+p=2, and m=1 to 5;

y=1 or 2, y=2 with the proviso that when w=0 then Y is —W—R³⁴—W¹—, or

and in formula (J) when z=1 and in formulas (G) and (H) at least one Zor Z¹ is —SR³².

The preferred diorganotin compounds used in the pr actice of th isinvention are those compounds according to formula (F) where R is methylor butyl, R³¹ is methyl or butyl and W is sulfur; those compoundsaccording to formula (G) where R is methyl or butyl, R³¹ is methyl orbutyl, Z is —SR³² where R³² is

and Z¹ is —SR³² is

those compounds according to formula (H) where R³⁰ is methyl or butyl,R³¹ is methyl or butyl, Y is —S—, Z is —SR³² where R³² is

Z¹ is —SR³² where R³² is

m=1, n=2 and p=0; and those compounds according to formula (J) where R³⁰is methyl or butyl, R³¹ is methyl or butyl, Z is —SR³² and R³² is

Y is —S—, w=1, y=1 and z=1.

Examples of diorganotin compounds according to formula (F) include, butare not limited to, the compounds illustrated in Table 5 below.

TABLE 5 (F)

Diorganotin Compound No. R³⁰ R³¹ W 1 —C₄H₉ —C₄H₉ S 2 —C₈H₁₇ —C₈H₁₇ O

Examples of diorganotin compounds according to formula G include, butare not limited to, the compounds in Table 6 below.

TABLE 6 (G)

Diorganotin Compound No. R³⁰ R³¹ Z and Z¹ C

Same as R³⁰

D —CH₃ Same as R³⁰

Examples of diorganotin compounds according to formula (H) include, butare not limited to, the compounds in Table 7 below.

TABLE 7 (H)

Diorganotin Compound No. R³⁰ and R³¹ Z Z¹ Y n p m E —CH₃

Same as R³⁰ —S— 1 1 1 F —C₄H₉

Same as R³⁰ —S— 1 1 1

Examples of diorganotin compunds according to formula (J) include, butare not limited to, the compounds in Table 8 below.

TABLE 8 (J)

Diorganotin Compound No. R³⁰ R³¹ Z Y w y z G —C₄H₉ —C₄H₉

—S— 1 1 1

The mono-organotin compounds and diorganotin compounds useful in thecompositions of this invention may be prepared by methods well-known inthe art such as the reaction of a mono- or dialkyltin chloride with amercaptoalkyl carboxylate or an alkyl thioglycolate in the presence of abase to scavenge hydrogen chloride. Methyltin trichloride, dimethyltindichloride, butyltin trichloride, dibutyltin dichloride, ethylhexyltintrichloride, and dioctyltin dichloride are examples of organotin halidesthat are suitable for the preparation of useful stabilizers for thisinvention. See for example, U.S. Pat. Nos. 3,565,930, 3,869,487,3,979,359, 4,118,371, 4,134,878 and 4,183,846 all of which areincorporated herein by reference.

Monosulfides and/or polysulfides of the mercaptoalkyl carboxylates andalkyl thioglycolates are also suitable as metal based stabilizers in thecompositions of this invention for improving the resistance ofhalogen-containing polymers to deterioration when heated to 350° F.(177° C.) during processing. Polysulfides are mixtures of compoundshaving from 2 to 10 or more sulfur atoms linked together but compoundshaving from 2 to 4 sulfur atoms are preferred along with themonosulfides. Said sulfides are made by heating stoichiometricquantities of a mercaptoalkyl ester or alkylthiocarboxylate and anorganotin chloride in water and ammonium hydroxide to about 30° C. (86°F.), slowly adding an alkali metal mono- or polysulfide, and heating thereaction mixture further to about 45° C. before separating the productfrom said mixture. The sulfides may be described as a blend of thereaction products which are believed to include the monosulfides andpolysulfides of the mercaptoalkylesters and thioglycolates. Saidsulfides contain from about 10 to about 42% by weight of tin and fromabout 8 to about 42% by weight cf sulfur. The sulfides of themercaptoalkyl esters and their preparation are described in U.S. Pat.No. 4,062,881. These sulfides are believed to include thebis[(monoorganotin) bis(mercapto-alkylcarboxylate)] monosulfides andpolysulfides, and bis[(diorganotin)mono(mercaptoalkyl-carboxylate)]monosulfides and polysulfides, and products which arise duringequilibrium reactions among said mono- and polysulfides. The chemicaland patent literature contain numerous examples demonstrating thatmembers of different classes of organotin compounds may react with oneanother under certain conditions to yield products containing one ormore tin atoms wherein at least a portion of the tin atoms are bonded todifferent combinations of radicals than they were before being mixedtogether.

Conventional non-metallic stabilizers and antioxidants can also beincluded in the stabilizer compositions of the present invention toassist in improving the properties of the halogen containing resin.Thus, there can be included 0.01-10%, preferably 0.1-5% based on theresin of sulfur containing compounds such as dilauryl-thiodipropionate,distearyl 3,3′-thiodipropionate, dicyclohexyl-3,3-thiodipropionate,dioleyl-3,3′-thiodipropionate, dibenzyl-3,3′-thiodipropionate,didecyl-3,3′-thiodipropionate, dibenzyl-3,3′-thiodipropionate,diethyl-3,3′-thiopropionate, lauryl ester of 3-methylmercaptopropionicacid, lauryl ester of 3-butylmercaptopropionic acid, lauryl ester of3-lauryl mercaptopropionic acid, and phenyl ester of 3-octylmercaptopropionic acid.

Phenolic antioxidants can also be added in an amount of 0.01-10%,preferably 0.1-5% of the halogen-containing resin. Examples of suchantioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole,propyl gallate, 4,4′-thiobis(6-t-butyl-m-cresol),4,4′-cyclohexylidenediphenol, 2,5-di-t-amyl hydroquinone,4,4′-butylidene bis(6-t-butyl-m-cresol), hydroquinone monobenzyl ether,2,2′-methylene-bis(4-methyl-6-t-butyl phenol), 2,6-butyl-4-decyloxyphenol, 2-t-butyl-4-dodecyloxy phenol, 2-t-butyl-4-dodecyloxy phenol,2-t-butyl-4-octadecyloxy phenol, 4,4′-methylene-bis(2,6-di-t-butylphenol), p-amino phenol, N-lauryloxy-p-amino phenol,4,4′-thiobis(3-methyl-6-t-butyl phenol), bis [o-(1,1,3,3-tetramethylbutyl)phenol] sulfide, 4-acetyl-β-resorcylic acid, A-stagep-t-butylphenolformaldehyde resin, 4-dodecyloxy-2-hydroxybenzophenone,3-hydroxy-4-(phenylcarbonyl) phernyl palmitate, n-dodecyl ester of3-hydroxy-4-(phenyl carbonyl) phenoxyacetic acid, and t-butyl phenol.

The use of epoxy compounds in an amount of 0.01-5% in the polymercompositions is also valuable. Examples of such epoxy compounds includeepoxidized soya bean oil, epoxidized lard oil, epoxidized olive oil,epoxidized linseed oil, epoxidized castor oil, epoxidized peanut oil,epoxidized corn oil, epoxidized tung oil, epoxidized cottonseed oil,epichlorhydrin/bis-phenol A resins, phenoxy-propylene oxide,butoxypropylene oxide, epoxidized neopentylene oleate, glycidylepoxystearate, epoxidized α-olefins, epoxidized glycidyl soyate,dicyclopentadiene dioxide, epoxidized butyl toluate, styrene oxide,dipentene dioxide, glycidol, vinyl cyclo-hexene dioxide, glycidyl etherof resorcinol, glycidol ether of hydroquinone, glycidyl ether of1,5-dihyroxynaphthalene, epoxidized linseed oil fatty acids, allylglycidyl ether, butyl glycidyl ether, cyclohexane oxide,4-(2,3-epoxypropoxy) acetophenone, mesityl oxide epoxide,2-ethyl-3-propyl glycidamide, glycidyl ethers of glycerine,pentaerythritol and sorbitol, and 3,4-epoxycyclohexane-1, 1-dimethanolbis-9,10-epoxystearate.

Likewise there can be used organic phosphites in an amount of 0.01 to10%, preferably 0.1-5% of the halogen containing resins. The organicphosphites contain one or more, up to a total of three, aryl, alkyl,aralkyl and alkaryl groups, in any combination. The term “trialkylaryl”is inclusive of alkyl, aryl, alkaryl and aralkyl phosphites containingany assortment of alkyl, aryl, alkaryl and aralkyl groups. Exemplary aretriphenyl phosphite, tricresyl phosphite, tri(dimethylphenyl) phosphite,tributyl phosphite, trioctyl phosphite, tridodecyl phosphite, octyldiphenyl phosphite, dioctyl phenyl phosphite, tri(octyl-phenyl)phosphite, tri(nonylphenyl) phosphite, tribenzyl phosphite, butyldicresyl phosphite, octyl di(octyl-phenyl) phosphite, tri(2-ethyl-hexyl)phosphite, tritolyl phosphite, tri(2-cyclohexylphenyl) phosphite,tri-alpha-naphthyl phosphite, tri(phenylphenyl) phosphite, andtri(2-phenylethyl) phosphite.

Likewise there can be included polyol stabilizers for vinyl chlorideresins in an amount of 0.01-10%. Thus there can be included glycerol,sorbitol, pentaerythritol and mannitol.

Nitrogen containing stabilizers such as dicyandiamide, melamine, urea,formoguanamine, dimethyl hydantoin, guanidine, thiourea,2-phenylindoles, aminocrotonates, N-alkyl and N-phenyl substitutedmaleimides, wherein the alkyl group has from 1 to 4 carbon atoms, andthe like also can be included in amounts of 0.1-10%. There can even beincluded conventional lubricants for vinyl chloride resins such as lowmolecular weight polyethylene, i.e. polyethylene wax, fatty acid amides,e.g. lauramide and stear-amide, bisamides, e.g. decamethylene, bisamide, and fatty acid esters, e.g. butyl stearate, glyceryl stearate,linseed oil, palm oil, decyloleate, corn oil, cottonseed oil,hydrogenated cottonseed oil, etc.

The stabilizer compositions of this invention may be prepared byblending the components thereof in any convenient manner which producesa homogeneous mixture, such as by shaking or stirring in a container.Likewise, the stabilized compositions of this invention can beincorporated in the halogen-containing organic polymer by admixing thestabilizer composition and polymer, such as, for example, in anappropriate mill or mixer or by any other of the well-known methodswhich provide uniform distribution of the stabilizer throughout thepolymer.

The stabilizer compositions of this invention are employed in an amountsufficient to impart the desired resistance to heat deterioration tohalogen-containing organic polymers. It will be readily apparent to oneof ordinary skill in the art, that the precise amount of stabilizercomposition used will depend upon several factors, including, but notlimited to, the particular halogen-containing organic polymer employed,the temperature to which the polymer will be subjected, and the possiblepresence of other stabilizing compounds. In general, the more severe theconditions to which the halogen-containing organic polymer issub-jected, and the longer the term required for resisting degradation,the greater will be the amount of stabilizer composition required.Generally, as little as about 0.20 part by weight of the stabilizercomposition per hundred parts by weight of halogen-containing organicpolymer will be effective. While there is no critical upper limit to theamount of stabilizer composition which can be employed, amounts inexcess of about 10 parts by weight of halogen-containing organic polymerdo not give an increase in effectiveness commensurate with theadditional amount of stabilizer employed.

The following examples further illustrate the preparation of blockedriercaptans of this invention, the preparation of stabilizercompositions of this invention, and the advantages of said blockedmercaptans and stabilizer compositions.

EXAMPLES 1-14

The starting materials, the procedure for preparing the latentmercaptans and the percent of residual —SH groups in the latentmercaptan are given in TABLE 9. The total color change of PVCcompositions containing said latent mercaptans as part of stabilizercompositions in contrast to that of PVC compositions which are otherwisethe same but without the latent mercaptan of this invention are given inTABLE 10.

A standard PVC pipe formulation containing:

INGREDIENT AMOUNT PVC (Shintech SE950) 100.00 Calcium carbonate 5.00 phrTitanium dioxide 1.00 ″ Calcium stearate 0.60 ″ Oxidized polyethylene0.15 ″ Paraffin wax 1.20 ″ Tin mercaptide of a mercaptoalkyl 0.25 ″carboxylate

was processed as the Control on a standard two-roll mill at 199° C. withchips taken at one-minute intervals. Then the same formulation exceptfor the addition of the indicated amount of latent mercaptan was alsoprocessed on the same roll at the same temperature, taking chips at thesame intervals. The total color change (dE), relative to a white tilestandard, was measured using a Hunter calorimeter. The dE values givenin TABLE 10 for the Control are averages of the values measured in the12 tests which paralleled the tests of the stabilizer compositions ofExamples 1-12.

EXAMPLES 15-18

The standard PVC pipe formulation of Examples 1-14 was used and the heatstabilization afforded by latent mercaptans of FORMULAS 4, 2, and 18were tested at different levels as shown in Table 11.

TABLE 9 Example No. FORMULA Procedure % SH  1 2 A 0.31  2 3 A 0.10 3^(*) 4 A 0.17  4 10 A 0.10  5 11 B 0.10  6 12 C 0.20  7 13 B 13.2  814 A 0.10  9 15 E 0.10 10 16 D 0.35 11 17 D 0.30  12^(**) 18 A 0.25 1321 A 0.30 14 25 C 0.20 *Also contains minor amounts of FORMULAS 5-9.**Also contains minor amount of 19.

TABLE 10 Example dE at One-minute Intervals phr 1 2 3 4 5 6 7 8 9 10Control — 5.6 7.2 8.1 9.4 11.2 13.7 17.0 20.8 23.8 25.7 1 0.10 3.9 4.24.6 5.5 8.3 12.1 16.6 20.0 23.6 26.7 2 0.15 4.0 3.9 4.7 5.5 7.0 10.314.0 17.6 22.1 26.2 3 0.15 4.0 4.7 4.6 5.2 6.7 8.5 11.3 14.1 18.0 21.3 40.28 3.9 5.0 5.5 6.1 7.6 11.7 16.7 20.5 24.2 25.5 5 0.25 5.3 6.2 6.8 7.79.3 13.8 18.3 22.1 24.2 25.5 6 0.04 3.0 3.5 4.4 5.8 9.5 13.8 18.3 22.223.9 25.6 7 0.12 4.9 5.7 6.5 6.8 7.6 8.9 11.1 14.3 17.1 20.9 8 0.15 6.66.7 7.0 7.2 7.8 9.9 12.3 16.3 20.1 23.3 9 0.20 4.3 5.3 6.3 8.5 10.9 14.618.6 22.2 24.5 26.8 10  0.30 4.9 5.2 5.6 6.5 7.5 10.6 14.8 18.5 22.024.2 11  0.25 6.3 6.6 6.5 7.0 8.2 11.6 16.0 19.4 22.0 23.1 12  0.10 3.54.3 5.4 6.4 8.0 10.7 14.1 17.4 21.4 24.7 13  0.10 4.1 4.7 4.7 5.5 6.710.0 13.8 17.4 20.1 22.8 14  0.10 4.7 5.6 6.0 6.6 7.3 8.2 16.3 12.9 16.118.6

TABLE 11 Example dE at One-minute Intervals FORMULA phr 1 2 3 4 5 6 7 89 10 Control — — 5.6 7.2 8.1 9.4 11.2 13.7 17.0 20.8 23.8 25.7 15 4 0.284.2 4.6 4.9 5.9 7.6 10.7 13.0 16.5 20.2 24.6 16 2 0.28 3.8 4.0 4.7 5.37.6 10.0 13.2 16.8 21.5 26.3 17 4 0.03 4.4 5.4 5.9 6.4 6.6 7.8 10.0 12.414.7 17.1 18 18  0.05 3.5 5.4 5.3 6.2 7.5 8.7 10.2 12.7 10.3 17.8

EXAMPLE 19

A standard clear PVC formulation containing:

INGREDIENT AMOUNT PVC (OCCIDENTAL 190) 100.00 PROCESS AID  1.50 phrIMPACT MODIFIER  6.00 ″ LOXIOL G-16  1.00 ″ LOXIOL G-70  0.70 ″ OXIDIZEDPOLYETHYLENE  0.20 ″ EPOXIDIZED SOYBEAN OIL  1.00 ″METHYLTINTHIOGLYCOLATE  1.25 ″

was processed as a Control on a standard two-roll mill (30F/40R) at 187°C. with chips taken at two-minute intervals. Then the same formulationexcept for decreased stabilizer level and the addition of the amount oflatent mercaptan shown below was also processed on the same roll at thesame temperature, taking chips at the same intervals. The total colorchange (dE) was measured versus a white tile standard using a Huntercolorimeter.

INGREDIENT AMOUNT (PHR) METHYLTINTHIOGLYCOLATE 1.00 COMPOUND #4 0.25

TABLE 12 dE at Two Minute Intervals 2 4 6 8 10 12 14 16 18 20 22 Control15.0 15.9 17.1 17.3 18.7 20.1 21.5 23.6 26.8 31.7 38.2 Ex. 19 15.1 14.615.1 15.4 15.7 16.9 18.5 20.7 23.7 27.3 34.5

EXAMPLE 20

¹H-NMR spectroscopy was used to determine the molecular structure of2-S-(tetrahydropyranyl)thioethyldecanoate (FORMULA 24) which wasprepared by adding 42.0 grams (0.50 mole) of 3,4-dihydropyran to 112.2grams (0.50 equivalent) of mercaptoethyldecanoate (14.7% SH) over aperiod of 45 minutes while maintaining a nitrogen atmosphere and atemperature below 35° C. and then heating it to 50° C. and holding thattemperature for 1.5 hours. After cooling the solution, it was washedwith two 200 ml portions of a 10% sodium bicarbonate solution in water,followed by a 200 ml wash with water. The organic layer was dried withMgSO₄ to yield a light yellow liquid having an SH content of less than0.5 percent as determined by titration with a 0.100 N iodine solution inisopropanol. The ¹H-NMR (CDCl₃, δ) spectrum was: 2.3 (2H, t, —C(═O)—CH₂—CH ₂), 2.8 (2H, m, —S—CH ₂—CH ₂—), 4.2 (2H, m, —S—CH ₂CH ₂—O—), 4.9(1H, m, —O—CH(—S—CH ₂—)—CH ₂—CH ₂—). The total color change (dE) of aPVC composition containing 0.13 phr of the latent mercaptan of thisexample was measured versus a white tile standard using a Huntercalorimeter at one mintue intervals. At one minute, it was 4.2; at fivemintues, it was 8.4.

EXAMPLE 21

¹H-NMR spectroscopy was used to determine the molecular structure of1-S-(2-hydroxyethylthio)-1-phenylmethane (FORMULA 11) which was preparedby adding 135.0 grams of a 20% methanol solution of sodium methoxide to39.1 grams (0.50 mole) of 2-mercaptoethanol and 63.3 (0.50 mole) gramsof benzyl chloride under nitrogen over a period of 45 minutes whilekeeping the temperature below 50° C., then heating the solution to 60°C. and holding it there for 6 hours. After cooling the solution, it waswashed with two 200 ml portions of. water, dried with magnesium sulfate,and stripped of solvent at 90° C. and 10 mm Hg to yield a light yellowliquid having an SH content of less than 0.5 percent as determined bytitration with a 0.100N iodine solution in isopropanol. The ¹H-NNR(CDCl₃, δ) spectrum was: 2.6 (2H, t, —S—CH ₂—CH ₂—OH), 3.6 (2H, t,—CH₂—CH ₂—OH), 3.7 (2H, s, Ar—CH ₂—S—), 7.3 (5H, m, Ar—H) the ¹³C-NMR(CDCl₃, δ) spectrum was 33.9 (—S—CH₂—), 35.8 (Ar—CH₂—) and 126.9-138.6(Ar).

EXAMPLE 22

¹H-NMR spectroscopy was used to determine the molecular structure of1-S-(2-hydroxyethylthio)-1-(2-hydroxyphenyl)methane (FORMULA 12) whichwas prepared by heating a stirred mixture of 31.5 grams (0.40 mole) of2-mercaptoethanol and 50 grams (0.40 mole) of 2-hydroxy benzyl alcoholin 75 grams of toluene to 40° C. under nitrogen and adding 0.21 gram of70% methanesulfonic acid, heating it to 65° C. and holding it there for45 minutes. After cooling the solution, it was washed with 100 mls of10% aqueous sodium bicarbonate and 100 mls of water, dried withmagnesium sulfate, and stripped of solvent at 50° C. and 10 mm Hg toyield a tan viscous oil having an SH content of less than 0.3 percent asdetermined by titration with a 0.100N iodine solution in isopropanol.The product was purified by column chromatography through silica gelusing ethyl acetate/methanol as the elution solvent to obtain a lightyellow oil. The ¹H-NMR (CDCl₃, δ) spectrum was: 2.5 (2H, t, —S—CH₂—CH₂—), 3.6 (2H, t, —CH₂—CH ₂—OH), 3.7 (2H, s, Ar—CH ₂—S—), 6.6-7.2(5H, m, Ar—H); the ¹³C-NMR (CDCl₃, δ) spectrum was 31.1 (—S—CH₂CH₂—),33.5 (Ar—CH₂—S—), 61.1 (—CH₂ CH₂—OH and 116.5-154.3 (Ar).

EXAMPLE 23

¹H-NMR spectroscopy was used to determine the molecular structure of1-S-(2-hydroxyethylthio)-1-methyl-1-N-pyrrolidinonylmethane (FORMULA 2)which was prepared by adding 55.57 grams (0.50 mole) of 1-vinyl-2pyrrolidinone with stirring to a solution of 39.06 grams (0.50 mole) of2-mercaptoethanol and 0.14 gram of 70% methanesulfonic acid whilemaintaining the temperature below 40° C. and an atmosphere of nitrogenin the reaction vessel. The reaction mixture was heated to 60° C. andheld there for one hour. After cooling the solution, it was diluted with75 mls of diethyl ether, washed with two 100 ml portions of water and 25mls of saturated aqueous sodium bicarbonate, dried with magnesiumsulfate, and stripped of solvent at 50° C. and 10 mm Hg to yield a lightyellow oil having an SH content of less than 0.5 percent as determinedby titration with a 0.100N iodine solution in isopropanol. The ¹H-HMR(CDCl₃, δ) spectrum was: 1.4 (3H, d, CH ₃—CH<), 2.1 (2H, q, >N—CH ₂—CH₂—CH₂—), 2.4 (2H, t, —S—CH ₂—CH ₂—), 2.5 (2H, t, —CH ₂—C(═O)—), 3.4 (2H,t, —CH₂—CH ₂—N<), 3.7 (2H, t, —CH₂CH ₂—OH), 5.6 (1H, q, >N—CH(—C₃)—S—);the ¹³C-NMR (CDCl₃, δ) spectrum was 17.7 (>CH—CH₃), 19.2(—CH₂—CH₂—CH₂—), 31.3 (CH₂—CH₂—C (═O)—), 33.4 (—S—CH₂CH₂—), 41.8(>N—CH₂—CH ₂—), 51.5 (>N—CH—(CH₃)—S—), 61.6 (—S—CH ₂ CH₂—OH). 175.5(—CH₂C(═O) —N<).

EXAMPLE 24

To 28.4 grams (0.36 mole) of 2-mercaptoethanol under nitrogen, there wasadded 0.22 gram of p-toluenesulfonic acid, immediately followed by theaddition of 60.0 grams (0.36 mole) of cresyl glycidyl ether withstirring over a period of 60 minutes while maintaining the temperatureat 50° C. The mixture was then heated to 65° C. and held there for 2.5hours. After cooling, the solution was washed with sodium bicarbonatetwo 150 ml portions of water containing 25 mls of saturated aqueoussodium bicarbonate solution, then dried with magnesium sulfate to yielda clear oil with <0.4% SH as determined by titration with 0.100 N iodinesolution in isopropanol. The molecular structure of the product,2-hydroxy-3-(2-hydroxyethylthio) propyl o-methylphenyl ether (FORMULA16), was determined by ¹H-NMR and ¹³C-NMR spectroscopy. ¹H-NMR(CDCl₃COCD₃, δ): 2.2 (3H, s, ArCH ₃), 2.8 (4H, m, —CH ₂—S—), 3.7 (2H, m,—CH ₂—OH), 4.1 (2H, dd, Ar—O—CH ₂—), 4.6 (1H, m, —CH(OH)—, 6.8-7.2 (4H,m, Ar—H); ¹³C-NMR (CD₃COCD₃, δ): 16.3 (Ar—CH₃), 36.8 (—S—CH₂—), 62.3(—C₂—OH), 70.1 (>CH—OH), 70.5 (Ar—O—CH₂—), 111.9-157.8 (Ar).

EXAMPLES 25 & 26

As another aspect of this invention, it has been discovered thatantioxidants activate the latent mercaptans to enhance the heatstability of PVC compositions during processing. The PVC pipeformulations of Example 25 (latent mercaptan alone) and Example 26(latent mercaptan+an antioxidant) are compared with the Control andComparative Example 1 (CE 1) in TABLE 14. Each was processed on astandard two-roll mill at 199° C. Chips of the PVC formulation weretaken at one-minute intervals. The enhanced heat stability of theformulation of Examples 26 is evident. As a comparison of the resultsfor the Control and CE 1 shows, the antioxidant does not, by itself,enhance the effect of the alkyltin mercaptide.

EXAM- INGREDIENT Control 25 PLE 26 Comp Ex 1 PVC (Shintech SE950) 100.00100.00 100.0 100.00 Calcium carbonate 5.00 5.00 5.00 5.00 Titaniumdioxide 1.00 1.00 1.00 1.00 Calcium stearate 0.60 0.60 0.60 0.60Oxidized polyethylene 0.15 0.15 0.15 0.15 Paraffin wax 1.20 1.20 1.201.20 Alkyltin mercaptide of a mercaptoalkyl carboxylate 0.25 0.25 0.250.25 Latent mercaptan * 0.00 0.15 0.15 0.00 IRGANOX 1010 antioxidant0.00 0.00 0.20 0.20 * Isomers of FORMULAS 4-9

TABLE 14 dE values at One Minute Intervals Ex. No. 1 2 3 4 5 6 7 8 9 1011 Cont. 6.2 7.5 8.3 9.5 11.2 13.2 16.8 20.6 23.7 25.2 27.2 25 4.0 4.85.0 5.6 7.1 9.4 12.7 15.6 18.7 22.0 25.2 26 4.3 4.6 5.0 5.2 5.9 7.7 10.213.2 15.8 18.8 21.5 CE 1 5.3 7.6 8.3 9.3 11.0 13.1 16.8 20.0 23.2 25.126.6

As was mentioned above, the latent mercaptans of this invention are alsointermediates for the preparation of primary heat stabilizers,anti-oxidants, anti-microbial agents, odor masks, and photostabilizers.Primary heat stabilizers, for example, may be made from latentmercaptans having a phenolic, carboxylate, or a free mercaptanfunctionality by reaction with a metal or organometal oxide, hydroxide,or halide such as calcium hydroxide, barium hydroxide, methyltintrichloride and dimethyltin dichloride. Phenols, for example, yieldcompounds having the general formula

AB_(b)

wherein

A is Sn, Ba, Ca, Al, Mg, monoalkyltin, dialkyltin, trialkyl tin, B is

m and n are 0 or 1, X is aryl, alkaryl, or haloaryl, R¹ through R⁶ arethe same as above, R⁸ is O or S , z is 1 or 2, and b is from 1 to 4.

As another aspect of this invention then, a compound of the FormulaAB_(b) wherein A is dibutyltin, B is

m=0, n=0, z=1; X is phenyl, R⁴ and R⁵ are hydrogen, R⁸ is O, R¹ ishydroxyethyl and b is 2,

was prepared by the reaction of dibutyltin oxide with1-S-(2-hydroxyethylthio)-1-(2-hydroxyphenylmethane) (FORMULA 12) asfurther described in Example 27.

EXAMPLE 27 AND COMPARATIVE EXAMPLE 2

Twenty grams (0.08 mole) of dibutyltin oxide, 29.61 grams (0.16 mole) of1-S-(2-hydroxyethylthio)-1-(2-hydroxyphenylmethane), and 150 mls oftoluene were heated under a nitrogen atmosphere in a round bottom flaskequipped with a Dean-Stark trap. The azeotropic distillation of waterwas carried out at 108-111° C. and the theoretical amount (0.7 ml) wascollected after about two hours. The toluene was removed by distillationat 10 mm Hg and a maximum temperature of 110° C. A yellow oil havinglittle or no odor was obtained. The theoretical tin content is 19.7%;the tin content found was 20.2%. A satisfactory product of thisinvention was thus obtained.

In TABLE 15, the stabilization of a standard PVC pipe formulation by theproduct of Example 27 at a level of 0.25 phr is compared with that ofdibutyltin diphenate at the same level (Comparative Example 2, madeaccording to the general procedure of Example 27 except that phenol wassubstituted for the 1-S-(2-hydroxyethylthio)-1-(2-hydroxyphenylmethane).The resulting formulations were processed on a standard two-roll mill at199° C. with chips being taken at one-minute intervals. The standardformulation, as follows, was tested as the Control:

PVC (Shintech SE950) 100.00 Calcium carbonate 5.00 Titanium dioxide 1.00Calcium stearate 0.60 Oxidized polyethylene 0.15 Paraffin wax 1.20

TABLE 15 dE at One-minute Intervals Example 1 2 3 4 5 6 Control 19.433.5 40.3 43.0 40.3 39.3 Comp Ex 2 12.4 22.1 33.0 35.7 35.7 34.1 27 7.915.3 21.7 29.5 36.8 41.3

EXAMPLE 28

To a solution containing 22.58 grams (0.106 mole)1-S-hydroxyethylthiol-1-(2-hydroxyphenyl)propane, 14.47 grams (0.053mole) 2-mercaptoethyl-(4-methoxybenzyl)thioacetate, 17.94 grams (0.177mole) triethylamine, and 50 ml of dichloromethane is added dropwise overa period of one hour at 8° C. a solution of 15.00 grams (0.053 mole) ofbutyltintrichloride in 50 ml dichloromethane with stirring under anitrogen atmosphere. The solution is then slowly warmed to 40° C. andheld for one hour after which it is cooled to room temperature,transferred to a separatory funnel, and washed twice with 150 ml ofwater. After drying with magnesium sulfate, the product is stripped ofsolvent at 50° C. under 15 mm pressure to yield an amber oil. Theproduct was analyzed for tin content, 14.5% (14.2% theory), andtitratable SH, 4.0% (4.0% theory). A satisfactory product of thisinvention was thus obtained. In the AB_(b) formula for this product, Ais monobutyltin, B is the same as in Example 27, and b is 3.

A standard pipe formulation containing the following components:

INGREDIENT AMOUNT PVC (Shintech SE950) 100.00 Calcium carbonate 5.00 phrTitanium dioxide 1.00 ″ Paraffin wax 1.20 ″ Calcium stearate 0.60 ″Oxidized Polyethylene 0.15 ″

was processed with 0.27 phr of the above protected mercaptan stabilizerand in the absence of stabilizer (CONTROL) on a standard two-roll mill(30F/40R) at 199° C. with chips taken at one minute intervals. The totalcolor change (dE) was measured versus a white tile standard using aHunter calorimeter and is shown in Table 16.

TABLE 16 dE at One-minute Intervals Example 1 2 3 4 5 6 7 8 9 10 Control19.0 30.8 37.4 41.5 41.4 41.8 41.9 38.6 37.6 36.2 28 5.8 8.0 9.7 11.012.9 15.2 17.1 19.4 22.3 24.3

Anti-oxidants also may be made from latent mercaptans having a phenolicor hydroxyl group by their reaction with phosphorus trichloride or aphosphite having one, two, or three alkoxy, aryloxy, aralkoxy,alkaryloxy, or haloaryloxy groups to give a

PQ_(p)B_(3−p)

compound wherein P is phosphorus, Q is an alkoxy, aryloxy, aralkoxy,alkaryloxy, or haloaryloxy radical, p is 1 or 2 and B is

wherein n is 0 or 1; z is 1 or 2; R¹ through R⁶ are as above in Formula1, X is aryl, haloaryl, or arylcycloalkyl, and R⁸ is 0.

Also, the latent mercaptans of this invention wherein the blocking orprotecting group includes chemical functionality may provide additionalbenefit in polymer processing and/or performance. The disagreeable odorgenerated by primary mercaptan-containing stabilizers during theprocessing of PVC is masked by latent mercaptans exemplified by thecompound of FORMULA 21, the compound of FORMULA 25 and their isomers andhomologs, as otherwise defined by Formula 1, at concentrations as smallas about 0.01 part of the latent mercaptan per hundred parts of thehalogenated polymer. Much larger amounts of the latent mercaptan may, ofcourse, be used but the maximum amount necessary to effect the maskingis about 0.1 phr and the preferred amount is about 0.05 phr. Thus, thisinvention provides a means for masking the odor of mercaptans whilemaintaining the function of the mercaptan as a synergist for improvedcolor-hold.

It also has been found that the latent mercaptans of this invention areuseful as the sole heat stabilizer for a flexible PVC formulation.Suitably, the amount of the latent mercaptan for this use may be fromabout 1% to about 10% by weight of the total weight of the stabilizedPVC composition. This use of the latent mercaptans of this invention isexemplified in Examples 29 and 30 and by the test results shown in Table17.

EXAMPLES 29 AND 30

A standard flexible PVC formulation containing:

INGREDIENT AMOUNT PVC (GEON 30) 100.0 DIOCTYL PHTHALATE  25.0 phrEPOXIDIZED SOYBEAN OIL  4.0 ″ OXIDIZED POLYETHYLENE  0.2 ″ STEARIC ACID 0.5 ″

was processed using a Brabender Plasticorder at 200° C./80 rpm withchips being taken at two minute intervals. Then the same formulationexcept for the addition of 5.0 phr of the latent mercaptan of theFormula indicated in Table 17 was also processed at the same intervals.The total color change (dE) was measured versus a white tile standardusing a Hunter colorimeter.

EXAMPLE 31

A standard flexible PVC formulation containing:

INGREDIENT AMOUNT PVC (GEON 30) 100.00 DIOCTYL PHTHALATE  25.00 phrEPOXIDIZED SOYBEAN OIL  4.00 ″ STEARIC ACID  0.50 ″ OXIDIZEDPOLYETHYLENE  0.20 ″ HYDROTALCITE  2.00 ″

was processed using a Brabender Plasticorder at 200° C./80 rpm wishchips taken at two minute intervals. Then the same formulation exceptfor a decreased part level of hydrotalcite, 1.00 phr, in conjunctionwith latent mercaptan (CMPD #4), 1.00 phr, was also processed at thesame intervals. The total color change (dE), measured versus a whitetile standard using a Hunter calorimeter, is shown in Table 18.

TABLE 17 dE at Two-minute Intervals Example 2 4 6 8 10 12 14 16 18 20 22Control 49.4 73.3 78.1 80.3 78.3 77.3 77.9 76.2 77.7 83.5 82.7 29 28.341.0 44.6 48.6 48.4 52.0 51.6 50.5 52.0 50.2 51.5 Formula #4 30 33.043.7 47.4 49.3 50.0 51.4 53.1 55.0 60.4 64.5 67.2 Formula #18

TABLE 18 dE at Two-minute Intervals Ex. 2 4 6 8 10 12 14 16 18 20 22 24Cont. 30.0 36.3 42.3 48.3 52.3 55.8 66.0 82.9 84.5 CHARRED — 31 28.536.0 42.2 44.9 45.2 47.4 58.2 73.5 73.7 70.7 68.7 66.3

The use of the latent mercaptans of this invention along with a mixedmetal heat stabilizer for flexible PVC formulations is shown in thefollowing example.

EXAMPLE 32

A standard flexible PVC formulation containing:

INGREDIENT AMOUNT PVC (GEON 30) 100.0 DIOCTYL PHTHALATE  25.0 phrEPOXIDIZED SOYBEAN OIL  4.0 ″ OXIDIZED POLYETHYLENE  0.2 ″ STEARIC ACID 0.5 ″ Ba/Zn PHENATE  2.5 ″

was processed as a Control using a Brabender Plasticorder at 200° C./80rpm with chips being taken at two minute intervals. Then the sameformulation except for the addition of 2.0 phr of the latent mercaptanof Formula 4 was also processed at the same intervals. The total colorchange (dE) was measured versus a white tile standard using a Huntercalorimeter.

EXAMPLE 33

A flexible PVC formulation, similar to that of Example 32 except thatthe amounts of dioctyl phthalate and epoxidized soy bean oil were 40 and8.58 phr, respectively, and the phenate was replaced by a mixture of amethyltin carboxylate (0.60 phr) and a zinc carboxylate (0.27 phr) wasused as a Control and 0.75 phr of the latent mercaptan of Formula 4 wasadded to exemplify this invention. Each was processed as in Example 32except that the Plasticorder was operated at 60 rpm. The color changesof the formulations of Examples 32 and 33 are given in Table 19.

TABLE 19 Example dE at Two-minute Intervals Minutes 2 4 6 8 10 12 14 1618 20 22 Control (32) 23.1 21.1 20.8 20.9 19.9 20.8 24.7 27.2 33.2 41.251.2 32 21.4 21.1 20.9 21.9 22.6 25.8 26.0 31.1 35.0 39.2 42.9 Control(33) 26.1 27.4 27.6 29.2 30.1 31.6 33.6 33.5 38.1 38.8 39.5 33 24.8 24.124.3 24.3 23.7 24.7 25.5 24.8 26.7 26.3 28.0 dE at Two-minute IntervalsMinutes 24 26 28 30 32 34 36 38 Control (CHARRED) 32 43.8 48.5 51.1 52.355.5 61.5 74.0 (CHARRED)

Example 34 below illustrates the use of a hybrid mercaptan of thisinvention which contains both a blocked mercapto group and a freemercaptan group. The hybrid structures, as in FORMULA 13 above, functionas ligands for metallic-based stabilizers and as heat stabilizers bythemselves. Table 20 shows the improved early color when the hybrid isused.

EXAMPLE 34 AND COMPARATIVE EXAMPLE 3

A standard PVC pipe formulation containing:

INGREDIENT AMOUNT PVC (Shintech SE 950) 100.00 Calcium carbonate  5.00phr Titanium dioxide  1.00 ″ Paraffin wax  1.20 ″ Calcium stearate  0.60″ Oxidized polyethylene  0.15 ″ Tin mercaptide of a mercapto-  0.25 ″alkyl carboxylate

was processed as a Control on a dynamic two-roll mill at 199° C.(30F/40R) with chips being taken at one minute intervals. Then the sameformulation except for the addition of 0.11 phr of2-mercaptoethylcaprate (Comparative Example 3) or 0.12 phr of the latentmercaptan of FORMULA 13 was processed at the same intervals. The totalcolor change (dE) was measured versus a white tile standard using aHunter calorimeter.

TABLE 20 dE at One-minute Intervals Example 1 2 3 4 5 6 7 8 9 10 11Control 5.7 7.6 8.8 9.6 11.4 13.1 16.5 19.7 22.9 25.2 26.6 CE 3 6.0 7.07.4 8.1 9.2 10.5 12.7 14.8 18.0 21.7 24.6 34 4.9 5.7 6.5 6.8 7.6 8.911.1 14.3 17.1 20.9 24.3 Formula #13

Latent riercaptans exemplified by the compounds cf FORMULAS 12 and 20have anti-oxidant properties that may find use in improving polymerprocessing and polymer performance. A compound of FORMULA 23 acts as aphotostabilizer in a polymer to retard discoloration and loss ofphysical properties caused by ultra-violet radiation.

The tendency of a free mercaptan to deactivate a biocide in a productcontaining a heat stabilizer composition as well is negated by the useof a latent mercaptan of this invention in combination with ametal-based stabilizer as the heat stabilizer composition. The latentmercaptan prepared by the reaction of 3,4-dihydropyran and2-mercaptoethanol (Formula 4), for example, when tested at a level of0.5 phr in vinyl films containing dibutyltin bis(2-phenylphenate) had nodetrimental effect on the anti-microbial activity of OBPA and Vinyzene®antimicrobials against staphylococcus aureus and klebsiella pneumoniaebacteria and a fungal mix including aspergillus niger, penicilliumpinophylium, chaetomium globosum, aureobasidium pullulans, andgliocladium virens.

A novel, commercially attractive method for making highly active PVCheat stabilizers which often function also as anti-oxidants, -UVstabilizers, odor masks, and/or anti-microbial agents has beendeveloped. It is cost-effective and straightforward. The methodcomprises the reaction of a para-substituted phenol with formaldehydeand an alkali metal hydroxide in dilute aqueous solution at atemperature up to about 60° C., preferably a maximum of about 50° C.,and still more preferably from about 35° to about 50° C. Thecondensation is quenched by cooling the reaction mixture below 20° C. toas low as about 0° C., the mixture is neutralized, the resultantcondensate is isolated without further purification and is furthercondensed with a mercaptan-containing compound such as is describedhereinabove according to Procedure C, also described hereinabove. On anequivalent weight basis, the ratio of the phenol to formaldehyde is from1:1 to about 1:1.25 and the ratio of the phenol to alkali metalhydroxide is about 1:1 but a 5 to 10% excess may be used. The totalconcentration of the phenol and formaldehyde reactants in the aqueoushydroxymethylation of the phenol is from about 25 to about 50% byweight. Examples of suitable phenols include bisphenol A,4,4′-dihydroxydiphenyl sulfone (bisphenol S), p-nonylphenol,p-tert-butylphenol, 2,4-di-tert-butylphenol, p-methoxyphenol,p-propylphenol, and p-cresol. Typical sources of formaldehyde includeaqueous solutions thereof, paraformaldehyde, neat formaldehyde, andcyclic oligomers thereof.

Examples 35-37 below illustrate the novel method and the activity of thelatent mercaptans produced is shown in Tables 21 and 22.

EXAMPLE 35

A nitrogen atmosphere is maintained in a 500 ml 3-neck flask equippedwith a condenser and a thermocouple while 20.0 grams (0.122 mole) of4-allyl-2-methoxyphenol (also known as eugenol) and 100 ml of 5.14weight/volume % of of aqueous sodium hydroxide solution are mixed withstirring while maintaining the temperature of the reaction mixture under35° C. When the mixture becomes homogeneous, 12.36 grams (0.153 mole) of37% aqueous formaldehyde solution is added over a ten minute period at35° C. and then the mixture is slowly heated to 50° C. and held therefor 3.5 hours, cooled, mixed with 100 ml of ethyl acetate and slowlyacidified with dilute hydrochloric acid to a pH of 3 with rapid stirringwhile maintaining the temperature under 20° C. The organic layer isseparated and then combined with a 100 ml ethyl acetate extract of theaqueous layer. The ethyl acetate solution is dried with magnesiumsulfate and stripped of solvent at 45° C./15 mm Hg for one hour. Both ¹Hand ¹³C NMR confirm that the amber liquid residue conforms to thedesired intermediate, 4-allyl-2-methoxy-6-hydroxymethyl phenol. Then, anitrogen atmosphere is established in a 3-neck, 250 ml flask equippedwith a condenser and a thermocouple and maintained while 20.0 grams(0.103 mole) of the intermediate and 8.05 grams (0.103 mole) of2-mercaptoethanol, and 100 ml of toluene, are stirred until homogeneous.The solution is heated to 40° C., 0.06 gram of methanesulfonic acid isadded, and the solution is further heated to 65-70° C. for 3 hours. Thesolution is cooled to 25° C., transferred to a separatory funnel andwashed with a saturated sodium bicarbonate solution to neutrality, driedwith magnesium sulfate, and stripped at 40° C./5 mm Hg for one hour. Theresidue is an amber liquid of pleasant odor with 0.1% residual —SHcontent, as determined by 0.100N iodine titration in isopropanol. Both¹H and ³C NMR confirm that the residue is4-allyl-2-methoxy-6-(2-hydroxyethyl-1S-thiomethyl)phenol as the majorproduct and unreacted intemediate as the remainder.

EXAMPLE 36

The general procedure of Example 35 was repeated except that 50 grams(0.333 mole) of p-tert-butyl phenol was used, along with 14 grams (0.35mole) of 98% sodium hydroxide and 33.73 grams (0.416 mole) of theformaldehyde solution to obtain the intermediate2-hydroxymethyl-4-tert-butyl phenol. The desired product,2-(2-hydroxyethyl)thiomethyl-4-tert-butyl phenol, was obtained from 17.2grams (0.095 mole) of the intermediate and 7.4 grams of the2-mercaptoethanol (0.095 mole) in 50 ml of toluene, along with 0.10 gramof the catalyst. Structural formula 26 for the product was confirmed by¹H and ¹³C NMR.

EXAMPLE 37

The general procedure of Example 35 was repeated except that 50 grams ofp-nonyl phenol (0.227 mole) was used, along with 9.73 grams (0.238 mole)of 98% sodium hydroxide and 23.0 grams (0.284 mole) of the formaldehydesolution to obtain the intermediate 2-hydroxymethyl-4-nonyl phenol. Thedesired product, 2-(2-hydroxyethyl)thiomethyl-4-nonyl phenol, wasobtained from 23.85 grams (0.095 mole) of the intermediate and 7.4 gramsof the 2-mercaptoethanol (0.095 mole) in 50 ml of toluene, along with0.10 gram of the catalyst. Structural formula 27 for the product wasconfirmed by ¹H and ¹³C NMR.

EXAMPLES 38-39

A standard PVC pipe formulation containing:

INGREDIENT AMOUNT PVC (Shintech SE 950) 100.00 Calcium carbonate  5.00phr Titanium dioxide  1.00 ″ Paraffin wax  1.20 ″ Calcium stearate  0.60″ Oxidized polyethylene  0.15 ″ Dimethyltin mercaptide  0.25 ″(ADVASTAB* TM-599T)

was processed as a Control on a dynamic two-roll mill at 187° C.(30F/40R) with chips being taken at one minute intervals. Theformulation of this invention (Example 39), made by the addition of 0.05phr of the product of Example 35 had a mild, yet decidedly pleasant odorduring processing on the two-roll mill under the same conditions. Thetotal color change (dE) and the Whiteness Index of each are shown inTable 21.

TABLE 21 Example 1 2 3 4 5 6 7 8 9 10 dE at one minute intervals Control4.6 6.3 7.0 7.5 8.1 9.4 10.7 12.1 14.4 16.8 39 3.9 4.6 4.8 5.1 5.7 6.78.5 10.8 13.7 16.5 Whiteness Index at one minute intervals Control 61.249.8 45.6 43.0 39.1 31.9 24.9 17.1 6.8 −6.5 39 63.6 58.0 57.3 54.5 50.545.1 35.5 24.1 8.8 −5.2

EXAMPLE 40

The standard PVC pipe formulation of Examples 38-39 was again used as aControl and was processed on a dynamic two-roll mill at 187° C.(30F/40R) with chips being taken at one minute intervals. Theformulation of this invention made by the addition of 0.03 phr of theproduct of Example 36 was processed under the same conditions. The totalcolor change (dE) and the Whiteness Index of each are shown in Table 22.

TABLE 22 Example 1 2 3 4 5 6 7 8 9 10 dE at one minute intervals Control4.4 6.1 6.6 7.4 7.9 8.7 10.1 11.6 13.1 15.9 40 3.6 4.4 4.3 4.8 5.3 6.58.0 10.6 13.3 15.5 Whiteness Index at one minute intervals Control 59.851.7 47.9 43.2 40.2 35.8 27.5 19.6 11.7 −2.1 40 62.8 60.9 59.7 58.9 53.846.7 38.9 25.1 10.9 −0.3

EXAMPLE 41 AND COMPARATIVE EXAMPLE 4

The standard PVC pipe formulation of Examples 38-39 was again used as aControl. The formulation of this invention made by the addition of 0.05phr of the product of Example 37. For comparison, a formulation was madeby the addition of 0.05 phr of nonylphenol to the Control. Each wasprocessed on a dynamic two-roll mill at 187° C. (30F/40R) with chipsbeing taken at one minute intervals. The total color change (dE) and theWhiteness Index of each are shown in Table 23.

TABLE 23 Example 1 2 3 4 5 6 7 8 9 10 dE at one minute intervals Control4.7 6.8 7.5 8.0 8.9 9.8 11.4 12.5 14.6 17.0 41 3.7 4.6 4.9 5.3 6.1 7.59.1 11.1 14.0 16.4 Comp Ex 4 4.7 6.6 7.2 7.5 8.1 9.1 9.9 11.5 13.7 15.9Whiteness Index at one minute intervals Control 57.7 46.6 42.5 41.0 35.430.1 20.8 15.5 4.0 −7.6 41 63.5 60.4 56.4 55.9 50.0 41.9 33.5 23.3 7.5−5.1 Comp Ex 4 59.4 48.0 44.8 43.2 39.2 33.8 29.8 20.9 9.2 −2.1

EXAMPLES 42-46

A standard flexible PVC formulation containing:

INGREDIENT AMOUNT Geon 30 PVC resin 100.00 Dioctyl phthalate 40.00Epoxidized soybean oil 8.58 Oxidized polyethylene 0.20 Stearic acid 0.50

was processed as the control on a standard two-roll mill at 199° C. withchips taken at two minute intervals. Then the same formulation exceptfor the addition of the indicated amount of proctected mercaptan andN-substituted maleimides was also processed on the same two-roll millunder the same conditions. The total color change, dE, relative to awhite tile standard, was measured using a Hunter calorimeter.

EXAMPLE INGREDIENT AMOUNT CONTROL NONE — 42 Mixture of Formulas 4-9 2.50phr 43 N-ethylmaleimide 2.50 phr 44 Mixture of Formulas 4-9 1.25 phrN-ethylmaleimide 1.25 phr 45 N-phenylmaleimide 2.50 phr 46 Mixture ofFormulas 4-9 1.25 phr N-phenylmaleimide 1.25 phr

TABLE 24 dE at two minute intervals Example 2 4 6 8 10 12 14 16 18 20Control 40.4 55.6 67.9 74.2 75.8 78.5 — — — — 42 25.9 35.0 44.1 45.947.8 49.2 49.8 50.6 51.1 52.1 43 28.6 41.2 52.9 58.9 59.6 63.5 — — — —44 26.8 32.9 40.1 40.7 43.1 43.7 45.7 45.9 46.9 48.3 45 33.8 43.0 53.459.4 62.4 61.5 — — — — 46 29.5 34.3 38.5 41.6 44.3 42.5 42.8 43.5 44.544.8

EXAMPLES 47-48 AND COMPARATIVE EXAMPLE 5

The stabilizing activities of 2-S-(tetrahydropyranyl)-thioethanol(Formula 4) and 2-S-(tetrahydropyranyl)thioethyl tallate, both preparedaccording to Procedure A hereinabove, and a thioether taught by Ludwigin U.S. Pat. No. 3,660,331 were compared by evaluating the color holdcapacities of flexible PVC compositions containing the following basecomposition and a stabilizer as indicated in Table 25 on a dynamictwo-roll mill at 350° F. (roll speed in rpm 30F/40R) on the yellownessindex, as shown in Table 25.

COMPONENT (TM or abbrev.) PARTS BY WEIGHT Polyvinyl chloride (GEON 30)100.0 Dioctyl phthalate (DIDP) 40.0 Epoxidized soybean oil (ESO) 5.0Stearic acid 0.2 Oxidized polyethylene 0.2 Ex. No. Stabilizer phr* 472-S-(2-hydroxyethylthio)tetrahydropyran 2.00 Zinc 2-ethylhexanoate(18%_(wt) zinc) 0.05 48 2-S-(dodecylthio)tetrahydropyran (Ludwig) 2.00Zinc 2-ethylhexanoate (18%_(wt) zinc) 0.05 CE 5 2-S-(2-hydroxyethylthio)tetrahydropyran 1.13** Zinc 2-ethylhexanoate (18%_(wt) zinc) 0.05 *Partsper hundred of PVC resin ** Sulfur content equal to Ex. 48

TABLE 25 Yellowness Index (YI) Time (Minutes) 5 10 15 20 25 30 35 40 4550 55 60 47 8.1 10.1 12.4 14.2 15.8 18.4 21.0 25.4 28.6 32.2 35.0 35.648 9.7 12.6 15.1 18.9 22.7 26.9 30.9 34.9 38.7 44.7 42.4 54.8 CE 5 9.411.0 13.6 13.8 17.7 20.1 24.6 29.8 34.6 40.9 45.9 55.2

EXAMPLE 49

2-S-(tetrahydropyranyl)thioethyltallate is prepared by adding 44.6 grams(0.53 mole) of 3,4-dihydropyran to 183.7 grams (0.50 equivalent) ofmercaptoethyltallate (9.0% SH) (made by the conventional esterificationof mercaptoethanol with tall oil acid) over a period of 45 minutes inthe presence of an acid catalyst while maintaining a nitrogen atmosphereand a temperature below 35° C. and then heating it to 50° C. and holdingthat temperature for 1.5 hours. After cooling the solution, it is washedwith two 200 ml portions of a 10% sodium bicarbonate solution in water,followed by a 200 ml wash with water. The organic layer is dried withMgSO₄ to yield a light yellow liquid having an SH content of less than0.5 percent as determined by titration with a 0.100 N iodine solution inisopropanol.

EXAMPLES 50-53 AND COMPARATIVE EXAMPLES 6-9

The flexible PVC compositions in Table 26 contain the same basecomposition as in Examples 47 and 48 but without the oxidizedpolyethylene and with the indicated stabilizer.

Ex. No. Stabilizer phr 50 2-S-(2-hydroxyethylthio) tetrahydropyran1.13*** 51 2-S-(2-hydroxyethylthio) tetrahydropyran 2.00 CE 62-S-(dodecylthio)tetrahydropyran (Ludwig) 2.00 522-S-(tetrahydropyranyl)thioethyl tallate 2.00 Zinc 2-ethylhexanoate (18%zinc) 0.05 CE 7 2-S-(dodecylthio)tetrahydropyran (Ludwig) 2.00 Zinc2-ethylhexanoate (18% zinc) 0.05 CE 8 2-S-(dodecylthio)tetrahydropyran(Ludwig) 1.25^(†) Zinc 2-ethylhexanoate (18% zinc) 0.05 532-S-(tetrahydropyranyl)thioethyl tallate 1.50 Conventional Ca/Znstabilizer 1.00 CE 9 2-S-(dodecylthio)tetrahydropyran (Ludwig) 0.94^(††)Conventional Ca/Zn stabilizer 1.00 ***Sulfur content equal to C.E. 6^(†)Sulfur content equal to Ex 52 ^(††)Sulfur content equal to Ex 53

TABLE 26 Yellowness Index (YI) Time (minutes) 5 10 15 20 25 30 35 40 4550 55 60 50 46.3 81.0 89.8 102.2 124.3 126.9 127.2 126.4 137.1 132.2122.4 113.2 51 48.4 81.9 93.6 103.0 112.1 112.9 122.2 131.2 124.2 130.3141.9 146.3 CE 6 56.4 99.7 117.5 124.3 137.4 138.2 150.1 152.8 153.7159.9 160.6 164.6 52 11.1 12.3 13.3 14.9 15.5 17.3 18.0 24.3 32.9 40.251.6 67.6 CE 7 10.5 12.0 14.6 17.1 20.7 24.2 28.9 34.0 40.3 48.0 54.563.3 CE 8 9.9 11.4 13.2 17.1 22.5 27.1 36.7 42.7 51.5 58.9 72.1 85.0 5311.2 12.7 14.7 16.8 18.5 20.5 23.6 28.9 37.0 54.9 106.2 burn CE 9 10.812.4 14.9 17.4 19.1 21.0 26.4 36.4 46.3 67.1 burn —

The dynamic thermal stability of the compositions of Examples 50 and 51and Comparative Example 5, as measured on the BRABENDER PLASTICORDERtest device at 200° C. and 80 rpm, is shown in Table 27.

TABLE 27 Dynamic Thermal Stability (minutes) 50 51.7 51 57.6 CE 6 57.3

EXAMPLE 54 AND COMPARATIVE EXAMPLES 10

An intermediate, 1-mercapto-2-hydroxypropyl isopropyl ether, was made bythe reaction of H₂S with isopropyl glycidyl ether in the presence oftriethylamine. The intermediate was then reacted with 3,4-dihydropyranaccording to Procedure A to make a latent mercaptan of this inventionhaving the formula

wherein a is 1, m and n are 0, X is oxygen, R³ and R⁷ join with X toform a heterocyclic moiety, and R¹ is alkoxy-hydroxyalkyl as it relatesto Formula 1. The stabilizing activity of theproduct,2-S-(tetrahydropyranyl)-1-isopropoxy-3-thio-2-propanol, was thencompared with that of the 2-S-(dodecylthio)tetrahydropyran of Ludwig inPVC rigid pipe-making compositions at equal sulfur content levels and atequal stabilizer use levels. The Whiteness Index of the compositionsduring processing on a two-roll mill at 390° C. was measured atone-minute intervals. The stabilizer compositions given below were addedto the basic composition as shown in Table 28. The basic composition hadthe formulation:

COMPONENT PARTS BY WEIGHT Polyvinyl chloride (k = 65) 100.0 Calciumcarbonate 5.00 Titanium dioxide 1.00 Paraffin wax 1.20 Calcium stearate0.60 Oxidized polyethylene 0.15 Ex. No. Stabilizer Compositions phr CE10 2-S-(dodecylthio)tetrahydropyran 0.18 Tin mercaptide (ADVASTABTM-599T) 0.20 54 2-S-(tetrahydropyranyl)1-isopropoxy- 0.15^(▴)-3-thio-2-propanol Tin mercaptide (ADVASTAB TM-599T) 0.20 552-S-(tetrahydropyranyl)1-isopropoxy- 0.18^(▴▴) -3-thio-2-propanol Tinmercaptide (ADVASTAB TM-599T) 0.20 ^(▴)Sulfur content equal to CE 10^(▴▴)Use level equal to that of CE 10

TABLE 28 PVC Color Hold (Whiteness Index) During Processing by Two-RollMill @ 390° F. (minutes) 1 2 3 4 5 6 7 8 9 10 11 12 CE 10 47.5 29.4 25.324.5 23.1 22.2 18.0 17.3 11.5 6.4 1.5 −2.6 54 46.0 40.4 36.4 37.2 35.633.5 32.3 26.9 19.2 10.2 14.8 −4.4 55 44.8 38.8 35.9 37.4 33.7 31.3 28.618.2 17.0 9.0 5.2 2.0

EXAMPLE 56 and COMPARATIVE EXAMPLES 11

The whiteness index of rigid pipe-making PVC compositions having theabove basic formulation and containing the following stabilizerformulations, measured as described above, is shown in Table 29.

Ex. No. Stabilizer Compositions phr CE 112-S-(dodecylthio)tetrahydropyran 2.00 Zinc octoate (18% zinc) 0.10 562-S-(tetrahydropyranyl)1-isopropoxy-3-thio-2- 2.00 propanol Zinc octoate(18% zinc) 0.10

TABLE 29 PVC Color Hold (Whiteness Index) During Processing by Two-RollMill @ 390° F. minutes 1 2 3 4 5 6 7 8 9 10 11 12 A 32.7 1.1 −9.7 −8.6−1.7 5.6 12.0 18.8 24.7 26.7 28.2 32.7 B 51.0 42.1 37.9 37.8 35.2 35.633.2 28.0 19.9 11.8 4.3 0.6

EXAMPLE 57

An intermediate, 1-mercapto-2-hydroxypropyl neodecanoate, was made bythe addition of H₂S to glycidyl neodecanoate in the presence oftriethylamine. An exothermic reaction between 20 parts by weight (0.049mole) of the product and 4.29 parts by weight (0.051 mole) of3,4-dihydropyran in the presence of methane sulfonic acid raised thetemperature of the mixture to 60° C. before it was cooled rapidly to 40°C. and held there for 5 hours. The product was taken up in ethylacetate, washed with aqueous sodium bicarbonate solution, water andbrine, then dried with magnesium sulfate and stripped to yield 20.9parts of 2-S-(tetrahydropyranyl)3-thio-2-hydroxypropyl neodecanoatecontaining only 0.28% SH. The R¹ radical of this latent mercaptan isneodecanoyloxy-hydroxypropyl.

EXAMPLE 58

Five hundred mls of heptane and 168 grams (1.12 moles) of the1-mercapto-2-hydroxypropyl isopropyl ether of Example 54 were charged toa one-liter round bottom flask equipped with a condenser and Dean-Starkcollector. Then 144.9 grams (1.75 moles) of propionic acid and 1.7 gramsof methane sulfonic acid were added. Twenty mls of water were collectedas the reaction mixture was heated at the 95° C. reflux temperature. Theproduct was chilled in an ice bath before excess acid was washed outwith aqueous sodium bicarbonate and brine. The product was dried withmagnesium sulfate and stripped to yield 217 grams of the isopropyl etherof 1-mercapto-2-propionoyloxypropane having a 13.89% SH content comparedto the theoretical value of 16.03%.

Ten grams (0.048 mole) of the ester and 3 drops of methane sulfonic acidwere charged to a 100 ml round bottom flask equipped with a magneticstirrer bar and an exothermic reaction raised the temperature to 60° C.when 4.28 grams (0.051 mole) of 3,4-dihydropyran was added. The mixturewas cooled and the reaction was continued at 40° C. for about 19 hours.The product had an SH level of 0.43%. The2-S-(tetrahydropyranyl)-1-isopropoxy-3-thio-2-propionoyloxypropane hasthe formula

wherein a is 1, m and n are 0, z is 1, X is oxygen, R³ and R⁷ join withX to form a heterocyclic moiety, and R¹ isisopropoxy-propionoyloxypropyl.

EXAMPLE 59

The adduct of 3,4-dihydropyran (DHP) and lauryl-3-mercaptopropionate wasmade by adding 8.6 grams (0.0102 mole) of the DHP over a 20 minuteperiod to 29.0 grams (0.1 mole) of the ester and 0.1 gram of methanesulfonic acid in an ice-cooled reactor; the exotherm warmed the mixtureto room temperature and heat was applied to continue the reaction at40-45° C. for 4 hours. The SH content of the product was only 0.44% byweight. The formula for the product is

wherein a is 1, m and n are 0, z is 1, X is oxygen, R³ and R⁷ join withX to form a heterocyclic moiety, and R¹ is dodecyloxycarbonylethyl.

EXAMPLE 60

Bis[2-S-(tetrahydropyranyl)thioethyl malonate] was prepared by charging30 grams (0.18 mole) of bis-(2-mercaptoethyl malonate) and 0.08 gram ofmethane sulfonic acid into a nitrogen-purged round bottom flask andadding 21.87 grams (0.26 mole) of DHP over a 15 minute period. Theexotherm raised the temperature to 50° C. and the mixture was held atthat temperature for 30 minutes. Gas chromatography showed that about90% of the product was the desired latent mercaptan. Residual startimgmaterials were stripped off by heating the mixture to 40° C. at 35 mmHg. Filtration gave a 79% yield of clear, low-odor product having an SHcontent of less than 0.05%. The generic R¹ radical is alkylenebis-(carbonyloxyalkyl).

EXAMPLE 61

A latent mercaptan of this invention having a dihydroxypropyl radical asthe R¹ radical of Formula 1 was prepared by stirring 108.2 grams (1.0mole) of 3-mercapto-1,2-propanediol and 0.49 gram of methane sulfonicacid in an ice-water cooled round bottom flask while adding 85.8 grams(1.02 moles) of DHP dropwise. The mixture was allowed to warm to roomtemperature for 15 minutes and then was heated to 40° C. for 4 hours.The SH content of the product was less than 1%. The formula of theproduct, 2-S-(tetrahydropyranyl)3-thio-1,2 propanediol, is

wherein a is 1, m is 0, n is 1, z is 1, X is oxygen, R³ and R⁷ join withX to form a heterocyclic moiety, and R¹ is dihydroxypropyl.

EXAMPLE 62

A latent mercaptan of this invention having a carboxyalkyl radical asthe R¹ of Formula 1 was prepared by cooling 69.44 grams (0.75 mole) ofthioglycolic acid and 0.33 gram of methane sulfonic acid in a roundbottom flask and adding 64.3 grams (0.765 mole) of DHP dropwise. Themixture was heated to 40° C. for 6 hours. The SH content was 0.06%. Theformula for the 2-S-(tetrahydropyranyl)thioglycolic acid is

wherein a is 1, m and n are 0, z is 1, X is oxygen, R³ and R⁷ join withX to form a heterocyclic moiety, and R¹ is carboxymethyl.

EXAMPLE 63

An intermediate,2-ethylhexyl mercapto-hydroxypropyl ether, was made bythe reaction of H₂S with 2-ethylhexyl glycidyl ether in the presence oftriethylamine. The intermediate was then reacted with 3,4-dihydropyranaccording to Procedure A to make a latent mercaptan of this inventionhaving the formula

wherein a is 1, m and n are 0, X is oxygen, R⁵ and R⁷ join with X toform a heterocyclic moiety, and R¹ is ethylhexoxy-hydroxypropyl as itrelates to Formula 1. The SH content was 0.26% by weight.

EXAMPLE 64

An intermediate, 1-mercapto-2-hydroxypropyl butyrate, was made by thereaction of H₂S with 10 grams of glycidyl butyrate wherein an exothermraised the temperature from 15 to 47° C. in the presence of 50 mlsmethanol and 9.7 mls triethylamine. The methanol and amine were strippedoff and the residue extracted with ethyl acetate. The extract was washedwith 0.1N HCl and brine, dried with magnesium sulfate and stripped toyield 9.7 grams of the inermediate. Five grams of the intermediate wasthen reacted exothermally with 1.81 grams of 3,4-dihydropyran withcooling according to Procedure A to make a latent mercaptan of thisinvention having the formula

wherein a is 1, m and n are 0, X is oxygen, R⁵ and R⁷ join with X toform a heterocyclic moiety, and R¹ is butanoyl-hydroxypropyl as itrelates to Formula 1. The SH content was 0.33% by weight.

EXAMPLE 65

A chelating agent is made in an acid catalyzed reaction of 411.3 grams(2 equivalents) of pyridoxine(3-hydroxy-4,5-dimethylol-2-methylpyridine) with 78 grams (1 equivalent)of mercaptoethanol and 138 grams (1 equivalent) of mercaptoethylether(HSCH₂CH₂OCH₂CH₂SH) to give a compound having Formula 35 below:

wherein, with reference to Formula 1, a is 2, m is 1, n is 0, y is 2, Xis phenyl, R¹ is ethoxyethyl, R⁶ is hydroxyl, one of the R⁷ radicals oneach ring is methyl, and the other is hydroxyethylmercaptomethyl.

EXAMPLE 66

An equimolar mixture of thioglycolic acid (124 grams) anddiethyleneglycol (106 grams) and a catalytic amount of methanesulfonicacid is heated to 100° C. at a pressure of 400 Torr and then heatedfurther to 120° C. as the pressure is reduced to 10 Torr over a periodof 2 hours to.reduce the acid number to less than 10. The product iswashed and dried. The mono-ester is the predominant product. The mixtureof reaction products is then reacted with an excess of 3,4-dihyropyranto obtain an adduct having an —SH content less than 0.1% by weight. R¹of Formula 1 for the principal product ishydroxy(polyethoxy)carbonylmethyl. A bright white pipe is obtained fromthe extrusion of a rigid PVC pipe formulation containing this product asa heat stabilizer.

EXAMPLE 67

A product having a structure and properties similar to those of theproduct of Example 66 is obtained when the same procedure is followedwith the exception of using triethyleneglycol in place ofdiethyleneglycol. In this case, R¹ of Formula 1 for the principalproduct is a hydroxy(polyalkoxy)carbonylalkyl radical wherein thepolyalkoxy chain has three units.

The acyloxy and benzoyloxy derivatives of thehydroxy(polyalkoxy)carbonylalkyl moiety are made by the conventionalesterification methods wherein the appropriate carboxylic acid isreacted with the hydroxyl group. Thetetrahydropyranyloxy(polyalkoxy)carbonylalkyl is made by a proceduresimilar to Procedure A hereinabove except for the use of the glycolderivative instead of a mercaptan. The etherification of thehydroxy(polyalkoxy) moiety with an alcohol such as propanol, benzylalcohol, or butanol is accomplished by heating a mixture of the glycolderivative, the alcohol, and an acid catalyst to drive off water ofcondensation.

EXAMPLE 68

The adduct of 3,4-dihydropyran and the methyl ester of N-acetyl cysteineis made by adding 8.83 gram (0.105 mole) of the DHP dropwise to 18 grams(0.102 mole) of the ester and 0.1 gram of methanesulfonic acid in anice-cooled reactor. The mixture is then warmed to 40-50° C. and heldthere for 4 hours. The product is the methyl ester of2-tetrahydropyranyl-N-acetyl cysteine. The R¹ radical in Formula 1 ismethoxycarbonyl(N-acetoamido)alkyl

Articles of manufacture contemplated by this invention, e.g. pipe, film,and window profile, are formed from the stabilized compositions of thisinvention by any of the well-known conventional techniques for formingpolymers into shaped articles.

While a few specific embodiments of this invention have been disclosedin considerable detail, variations and modifications of theseembodiments can be effected without departing from the spirit and scopeof the invention as disclosed and claimed herein.

What is claimed is:
 1. A compound having the formula AB_(b), wherein Ais dibutyltin, B has the formula:

m and n are 0, z is 1, X is phenyl, R², R³, and R⁶ are, independently,hydrogen, a hydroxyl, mercapto, acyl, alkyl, alkylenyl, aryl, haloaryl,alkaryl, aralkyl, hydroxyalkyl, mercaptoalkyl, hydroxyaryl, alkoxyaryl,alkoxyhydroxyaryl, or mercaptoaryl radicals having from 1 to 22 carbonatoms, R⁴ and R⁵ are hydrogen, R⁸ is O⁻, R¹ is hydroxyethyl, and b is 2.